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FAQs about Holes, Drilling for Plumbing Marine Systems, Fitting Size, Number & Placement

Related Articles: Plumbing Marine Systems by Bob Fenner, Myth of the One Inch Beast (Why Relying on One Inch Overflows... or Overflow! Is foolhardy) by Scott Vallembois, Plumbing Return Manifolds, Refugiums

Related FAQs: Holes & Drilling 1, Holes & Drilling 2, Holes & Drilling 3, Holes & Drilling 4,  & FAQs on: Rationale/Use, Designs, Fittings, Tools & Processes Themselves, Related Plumbing, Troubleshooting/Repair... Marine Plumbing 1, Marine Plumbing 2, Marine Plumbing 3, Marine Plumbing 4, Marine Plumbing 5, Marine Plumbing 6, Marine Plumbing 7, Plumbing 8, Plumbing 9, Plumbing 10, Plumbing 11, Plumbing 12, Plumbing 13, Plumbing 14, Plumbing 15 Plumbing 16, Plumbing 17, Make Up Water Systems, Pumps, Aeration, Circulation, Sumps, RefugiumsGear Selection for Circulation, Pump Problems Fish-Only Marine Set-ups, Fish-Only Marine Systems 2, FOWLR/Fish and Invertebrate Systems, Reef Systems, Coldwater Systems, Small Systems, Large SystemsWater Changes Surge Devices

Mmm, something in the way of a succinct stmt. re: The number, placement, size of overflows only approximates what sort of volume/flow you can expect to provide... "head", screening/sieving, plumbing, especially lateral/horizontal runs are indeed a huge factor... when/always in doubt, over-size, add more capacity... You'll be better off for this.

1 inch over flow bulk heads. 2/11/11
<Hey there.>
I have a question for you. I am one of the lucky ones that have 1 inch bulk heads the found you site and discovered there actual flow rates.
<You are not alone, the whole reason the testing was done!>
Is there any way to increase there flow rate?
<Sort of. I have been working (for 3 years now) on a follow up on doing just this. It is just a semi-complex DIY procedure. Basically taking your 1" bulkhead and using plastic epoxy to attach 1.25" PVC fittings to it.
Gets you another 100 GPH or so.>
I thought of venting the over flow return to the sump.
<Any overflow should be.>
I know in a house if your vent is plugged the flow is cut in half. Also would increasing the over flow return hose have any effect on the amount of water going through the bulk head e.g. 1 inch bulk head tied to 1-1/2 inch pvc pipe. Any experience or suggestions.
<If you have access to it I would drill the back of the tank inside the box for larger bulkheads. See: http://glass-holes.com/>
I have 150 gallon tank with a 60 gallon sup.2 1inch overflows and a Mag 18.
Thanks I wish I found this out 8 years ago, Would have used bigger over flow bulk heads.
<Well, we have all been there! I am sorry to tell you the flow rates listed in the article you are referring to were vented! People hate to hear it, but it is what it is! Scott V.>

Drilling Acrylic/Plumbing 12/10/10
<Hello Sanford>
I've reviewed what I can on the site. Can't find anything regarding my specific question. I want to drill a drain hole in the bottom of an acrylic tank (60 gallons, 1/4", bows a lot when full). I plan to build an overflow and have a standpipe inside. How close to the edge can I drill. I saw you tell another enthusiast 1" from the edge. That would work for me and my particular plans, but it would be a better solution if I could get a little closer. It seems to me that drilling through the bottom would give me some leeway. The stand top is a 3/4" sold piece of particle board.
<I would put a couple of coats of polyurethane on this board.>
Granted, I will need to cut through that to allow the drain pipe access to below. But it seems to me that there will still be a substantial amount of support to the bottom of the tank since it lays flat against the top of the stand. Any input would be great.
<First, I'd like to recommend you install a 1-1/2" standpipe. A one inch standpipe will only allow about a 350gph flow rate. See here. http://www.wetwebmedia.com/BulkheadFloRateArt.htm
With a 1-1/2" bulkhead fitting, I doubt you could get any closer than one inch from the edge. You have to allow room for the bulkhead fitting nut with molded flange
<You're welcome. James (Salty Dog)>

Adding a Bulkhead Brace to an Aquarium -- 11/16/10
I have a question for you guys.
I need to add a small piece of glass to an aquarium to hold a bulkhead for a sump return.
<<As in to 'beef-up' the area where the bulkhead will be installed? Not a bad idea in some instances, especially those dealing with very thin glass panes>>
The current return drops down in the center of the tank. The problem is I can't put a lid on it because the return is in the way and several fish have jumped out. I was going to get lids cut with a piece cut out of a corner at an angle then silicone a piece of glass on the top of the tank to hold the bulkhead fitting so I can remove the lids and still have the return in the tank.
<<Okay'¦'¦'¦'¦.me thinks I follow you'¦>>
My question is can I silicone this piece of glass on the aquarium with the fish in it?
<<As long as the area to which you are applying the Silicone/this brace is clean and dry'¦yes>>
Would the smell kill the fish?
<<In my experience, when effecting small repairs/modifications on aquaria with livestock present, the fumes from the Silicone have not proven to be problematic re>>
The perimeter bracing is about 2 inches wide so I can't see any other way to get a return line in the tank and still have lids on it. Any advice or any other ideas?
<<Drilling the tank through the back or end panels near the top (assuming it is not tempered glass), to install a bulkhead for the return line, is one option. Another might be to use a plastic grid material (e.g. -- plastic 'eggcrate') to cover the top of the tank to prevent the fishes jumping out, and cutting a 'tight fitting' opening for the return to pass through>>
<<Happy to share'¦ EricR>>

Where to Drill Holes for an Overflow? -- 12/04/09
Thanks for maintaining this great site.
<<Welcome'¦is quite the collaborative effort>>
I tried searching for my answer for a couple hours here, but there is just too much information to sort out. I have learned quite a bit about other things not related to my search however.
<<Very good>>
I have a non-drilled 75g acrylic tank 48x24x15. The tank has been up and running for a couple months without a sump, but now I think I want to add one.
<<A very useful adjunct>>
I was about to add a siphon-type overflow box but after reading through your site I have definitely decided against it.
<<Some mixed opinions for sure, with most I think considering exclusion of such the better option. But with some thought to redundant systems they can be utilized quite well'¦though my personal preference far and above is the 'drilled' gravity-drain type overflow>>
My next option would be to drain some of the water from the tank and drill a hole in the back and make some sort of overflow drain with a 90-degree elbow and some PVC.
<<This is a very doable design. I have similar throughputs/drains on my own reef display tank>>
Is this a good idea?
<<If done with care and good thought to the design/installation'¦yes it is>>
If so, where should I drill the hole?
<<On one of the non-viewable panels at least an inch in from the edge of the panel (this measurement is for 'Acrylic' tanks'¦I would allow more distance on a 'Glass' tank, for strength)>>
How far down?
<<This will depend on how you plan to handle the 'internal' component of the drain. If you simply plan to drill and install a bulkhead and screen (FYI -- the bulkhead screen will greatly diminish the flow capacity of the drain) then you will want to place the bulkhead very near the top of the tank by drilling the hole for the bulkhead with the upper edge about an inch from the top edge of the panel. This will give you a non adjustable water height in the tank of somewhere around the centerline of the bulkhead'¦dependant on the flow rate of the sump return pump. But might I suggest as a better alternative, to utilize a 90-degree ELL fitting on the inside of the drain bulkhead. Doing such gives you a means to 'vary' the water height in the tank by rotating the fitting to one side or the other, and you can even cut notches/teeth in to the fitting allowing you to place its upper rim closer to the top of the tank and providing a bit more 'security' re flushing small fishes to the sump (though I have found this risk to be very small). Such a setup also gives your drain much more flow capacity over the plain bulkhead w/screen>>
What size?
<<If installing only a single drain then go 2' if possible, though a 1.5' drain should also serve'¦with a 'pair' of the latter being your best option here in my opinion>>
Should I also drill a hole for the return while I'm at it or can I just pipe it in from the top?
<<You can go either way, your choice'¦though the former does 'look' better and won't be 'in the way' of a light hood/canopy if being used>>
Does the return hole need to be smaller?
<<For the size of your tank and the pump likely to be utilized, a 1' return will serve well>>
I obviously have no experience with setting up a sump.
<<Do peruse our site re'¦start here and follow/read among the associated links in blue (http://www.wetwebmedia.com/sumpdesfaq.htm)>>
If this is all a bad idea, what would you recommend?
<<I think this is a fine idea, with the right approach. I also want to mention'¦. When drilling the hole/s for the bulkhead fitting/s, be sure to use a properly sized 'Bi-Metal' hole-saw (be sure to research the proper hole-size for the bulkheads used) available at any hardware or home store. Also when drilling, take things slow and be sure to back the hole-saw out of the cut often. Acrylic is not difficult to cut/drill, but the heat build-up from the friction of the saw will start the Acrylic to melting'¦if you're going too fast and you stop for even a few moments, you can 'lock' the hole-saw in the cut and may have real trouble getting it free again>>
Thanks again for your wealth of knowledge!
<<Happy to share'¦ EricR>>

Re: Where to Drill Holes for an Overflow? -- 12/05/09
Thank you so much for your thorough response!
<<Happy to share!>>
I feel really confident now.
<<Ahh, good to know>>
The only thing I'm concerned about is drilling with the livestock still in the tank after I drain about 1/3 of the water.
<<Is not an issue'¦really>>
Any problems with fish, corals, and possible acrylic 'dust'?
<<Not in this instance'¦ Chips/dust will be minimal. You can try to scoop it out with a fine-mesh net if you want, but there really is no need for concern. Cheers'¦ Eric Russell>>

New Setup and Pump Questions 9/25/08 Hello Crew, <Hello there.> I've got a couple questions with a new set-up I'm about to start working with. I have a 110G 60 inch acrylic tank with one over flow box on the right wall with a 1" bulkhead. Then there are 3 3/4" bulkheads ( 2 on the left wall and 1 in the lower side) of the right wall next to the over flow box. My question is, would enough water siphon down Durso standpipe of a 1" bulkhead to accommodate a return pump of approx 800gph? <In a full siphon it would be close, you really do not want to utilize a siphon here. The two links below will shed some light on why. http://www.wetwebmedia.com/wdpbissues.htm http://www.wetwebmedia.com/overfloboxfaqs.htm More and larger throughputs/drains are really what is needed. If not, what would be the max gph pump to use? Would it be easy to perhaps make that 1" bulkhead 1.5"? <It can be done and worthwhile, perhaps multiple bulkheads if there is room enough in the box. Each 1.5 will give you a safe 750 gph, as opposed to 300 gph out of the 1'.> What tools, skills, or requirements would I need to perform this myself if recommended? <Basically just a drill, a hole saw and slight pressure. Since you already have a hole you will want to clamp something inside, over the hole, to guide the pilot bit until the hole saw itself starts to drill. This can be done freehand, but it is very difficult.> Any help would be appreciated. Thanks <Welcome, Scott V.>

A big "Thank You!" & Tank Dimensions/Overflows 7/20/08 Dear WWM Crew, <Jill> Thank you SO much for your outstanding commitment and hard work! The time you put into answering the daily FAQ's is a blessing. Thank you! <Thank you very much, glad the site has helped out!> I will be upgrading soon from a 7 gallon (saltwater) to a 75 gallon tank, which will eventually be an LPS dominated reef system. I have learned that three of the most important aspects of this hobby are researching, planning, and patience. <Stick to the above and you can't help but to be successful.> Before I make my large purchase, I wanted to ask you the following: in your opinion, which tank dimensions would be 'better'? 48'L x 18'W x 20'H or 60'L x 18'W x 16'H. Of course the word 'better' is subjective and dependent on the species being kept, but for the general overall health of the reef system, which would you prefer and for what reasons? <Taller tanks are tougher to work in, but 20' is not too tall unless you have very short arms. 16' is too short for my liking aesthetically, but if you like the look, go for it. The longer tank will technically provide a larger surface area for gas exchange, but the sump and skimmer will also provide gas exchange. The big difference I see is lighting. While a deeper tank requires more intense lighting, 20' is not overly deep. T5/PC/VHO can work fine at this depth for LPS. The longer tank will require longer and consequently higher wattage bulbs. Personally I would go for the 48' tank in this particular case, although, as you said, this is subjective and the next crew member may say 60'!> I have also decided on the Eheim 1262 (rated at 900 GPH) for the main pump. <My favorite pump.> In your opinion, would one overflow, or two work better in this system? <Always two, at the minimum. Three to four drains even in a system this size.> My research has led me to believe that one drain is preferable in a 48' system, while two is better in a 60'. <Has more to do with flow than the length of the system. Do distinguish overflow from the drains that actually provide the flow capacity.> Finally, do you believe that the standard overflow and drain pipes (as supplied by Tenecor reef ready tanks) would be appropriate for this pump? <You will want to make sure you have a minimum of two 1.5' drains or a single 2' to handle the flow from this pump. Double these drains if you wish to provide redundancy (you should).> Please accept my apologies if I have not supplied the correct information. I've researched the site for months and have purchased the CMA but still feel like a 'beginner' and have much to learn about this amazing hobby! <Keep reading, you will!> Thank you SO MUCH for your valuable advice! God bless! Jill <Welcome and thank you. Enjoy the new setup.>

Bigger Overflow Holes 4/9/08 Hello Crew! <Hello John.> Thank you for all that you do. You are appreciated and admired by aquarists and fish everywhere! <Thank you for the kind words and encouragement!> I have one quick question. I have been reading, over and over, that in many instances, the diameter of the overflow holes on the A.G.A. MegaFlow systems [factory-ready] is not large enough. <No, they are not really large enough.> Can you/would you name a glass aquarium manufacturer, who makes standard-size/pre-drilled (reef-ready) tanks that have BIGGER diameter holes than those found in the A.G.A. tanks? I've done MANY web searches for this information, and I keep coming up empty. <Most tank manufacturers will drill more/larger holes for you, for an extra fee of course. I have particularly found www.aqueonproducts.com (formerly AGA) to be great with their customer service. No long waits on the phone! Just give them a call and explain what you want, they will help you.> Much appreciated. Have a great day. John D. <Welcome and thank you. Have a great day also, Scott V.>

New Reef Tank Build'¦Holes In The Bottom Or the Sides? -- 03/06/08 Hey Eric - Linda from GA here. <<Hey Linda!!!>> I sold my 90 gal tank to my local fish guy months ago because I wanted to get a 75 or 90 gal drilled tank. <<A convert'¦cool!>> Well, now is the time. <<Yay!>> I still have my 1 yr. old 46 gal saltwater tank that I use the hang-on-back overflow box. <<Okay'¦will make a great sump>> It contains mostly Zoanthids, toadstool leather, Favia, mushrooms, and 5 small fish. <<I see>> The tank looks great and is so easy to maintain. <<Excellent>> Going to mess everything all up and transfer everything from it to a larger 75 or 90 gal tank. LOL <<Great times ahead'¦maybe you should go bigger!>> My main discussion is: Most tanks come drilled from the bottom left corner with built-in overflow... <<Most single-drain mass-production tanks, agreed>> I know in your previous email you stated you preferred the holes be drilled along the top sides. <<I did, yes>> I am totally new to drilled tanks. <<Ah'¦I think you will be pleased>> I would like to know why you prefer the holes to be drilled on the sides and not the bottom <<Well, think a bout it'¦if a bulkhead seal fails at the bottom of the tank'¦or two inches from the top of the tank'¦which one is going to 'completely drain the tank' if you aren't around? A little dramatic maybe'¦but quite the possibility. Also'¦which tank panel bears the bulk of the water-weight and is most susceptible to catastrophic failure from an improperly placed/drilled throughput? And'¦with throughputs up on the back/side panel of the tank, should something require attention you don't have to drain the entire system. Though admittedly, throughputs in the back panel may be difficult to get to if the tank is up against a wall>> and what the different is as far as performance. <<No real difference re performance'¦ I'm not telling you a bottom-drilled tank won't work, Linda'¦MANY hobbyists have them. Weigh the differences/benefits of both and use your own good judgment to choose>> I still have not decided whether I want a 75 or 90 gal. <<'I' am definitely of the opinion'¦bigger is better>> Not much difference, <<Oh contraire'¦the latter has 15g more volume!>> I guess, only one is taller, possibly harder to maintain? <<Not at all'¦ A larger water volume is more stable/less prone to rapid changes>> I already have access to another 90 gal non-drilled tank that comes with a CS90 hang on overflow box that this owner swears by and has a gorgeous reef system. <<I can't argue'¦many hobbyists also, utilize siphon overflows with good success>> Did some research on them and heard they are more reliable than the one I have but, even the people who make the CS90 say that a drilled tank is so much better. <<Indeed'¦the reliability of 'gravity' is unquestionable>> Am planning on drilling the sump-side of a large 200 wet/dry for an outside pump, which pumps 1300gph. (That alone is an upgrade for me instead of having the pump on the inside of the sump.) (grin) <<Hmm'¦even assuming a few hundred gph headloss, do figure on at least two 1.5' bulkheads for drains'¦three being better>> Also, wanted to run PVC from the drain down into the wet/dry and, of course, PVC return. PVC!!! Me??? <<Hee-hee!>> Another great improvement, although, I will admit I have a newbie fish-guy who is going to do most of this for me. <<Cool>> I also have access to a used 90 gal drilled tank with 3 1" holes drilled in the upper backside. I believe the guy said it was for a closed-loop, but I think that is advanced for my little fish guy who just started his own business. <<'¦! Perhaps he has started too soon then>> He seems to be mostly used to the bottom-drilled tanks or hang-on overflows and I really don't want anything too complicated for myself. <<Or him! (so it would seem)>> Thank you for answering my questions. <<You're always welcome, my friend>> Hope to hear from you soon. Linda in GA <<Do call on me if I can be of further assistance with your new tank installation. EricR in SC>>

Re: New Reef Tank Build'¦Holes In The Bottom Or the Sides? -- 03/08/08 Thank you Eric in SC, my good ol' southern gent! Lol <<Aw shucks, ma'am'¦twernt nuttin'¦>> Okay, mister <<Uh-oh!>> ...so if I bought the used tank that has the 3 1" holes drilled on the upper back side (which also has a built in corner overflow that has 2 holes drilled in the bottom!) how would I plumb this thing? <<Several options here I think. You could use the tank as is'¦plumb the drains through the bottom and a closed-loop through the back panel'¦or plumb the drains through the back panel and a closed-loop through the bottom'¦or'¦silicone a sheet of glass (same thickness as tank bottom and with a minimum two-inch overlap) over the holes in the bottom, forgoing the closed-loop and plumbing the drains through the back panel.>> You are right about my little fish guy (he is very young). He is the son of a local pet store owner. His first love is saltwater fish and is learning everyday...he is keeping things really simple and can do so here in this area where we live because there aren't many people until you reach Hotlanta that have saltwater. So, (laughing) he knows more than a lot of people here, which isn't saying a whole lot, but he is very eager and also learning by trial and error. <<I see'¦and likely won't be a problem as long as he is willing to do his research beforehand. Heck, we all have to start/learn somewhere. But, do make sure he can/will 'guarantee' his work'¦which may mean having to purchase/build on a 'new' tank>> He suggests that the basic built in corner overflow bottom-drilled tank can actually handle a Mag 12 and is using PVC for both drain and return. <<Mmm'¦ I wonder what he means by 'basic?' What an overflow can 'handle' (bottom-corner or otherwise) is based on the size of the overflow box and the size and number of throughputs/bulkheads. For the fore mentioned Mag-12, I would suggest two 1.5' bulkheads for the drain lines>> I've seen two identical systems in his Dad's store that he installed, along with about 6 businesses that he has installed. (The systems seem to be able to handle it, although one is kinda noisy.) <<Indeed, and likely overwhelming the drain(s)'¦do yourself a favor and go bigger than you (he) think you need, where your drain lines/throughputs are concerned>> The ones he has installed in the businesses and in his Dad's store are either the basic corner overflow bottom-drilled tank or siphon hang on overflow boxes. <<'Basic' is too general/means nothing'¦I need specifics (bulkhead size/number, siphon size/number, pump size, headloss, etc.) to be of much help/able to comment re>> I am sure he would love to try out something different but I really would appreciate someone at least knowing how to plumb the 3-1" holes. <<Depends on how they will be used>> So, I'm asking the wise one "How would I plumb this particular tank? <<Well Grasshopper'¦is pretty much up to you, as described previous>> What are the 3 1" holes for since it has a built in corner overflow with 2 drilled holes? <<This was likely a closed-loop'¦could have been two pump inputs (plumbed to a tee or Wye fitting'¦for the purpose of reducing the 'suction strength' a single input would impose) with a single return'¦or'¦a single input with two returns>> I know I mentioned a closed-loop, but thought they are something that goes around the entire perimeter of the inside of the tank. <<Not at all'¦ The use of a 'return-manifold' such as you describe is only one method of returning water to the tank....you can also simply 'tee-off' the return with outlets positioned at opposing ends of the tank'¦as well as other variations, only limited by your imagination and the flow capacity of the pump utilized>> Would the corner overflow holes be the drain and the 3-1" holes be the returns? <<Not likely'¦on this size tank>> Could they all tie into each other and then connect to the pump? <<This is a possibility'¦with the 'return' coming over the top edge of the tank>> See, now all this is getting complicated to me...I didn't want anything too complicated without having someone here knowledgeable as to all this plumbing stuff. <<A closed-loop is really quite simple'¦am sure you would agree if you were to see one>> (lol...now you quit that laughing at me, mister. Hey, SC isn't that far from GA...how 'bout you taking a little trip over this way and come over and help me out with this thing?!?!?! I mean, you are a southern gentleman, right?) (snicker, snicker) <<Hmmm'¦this sounds like coercion [grin]>> I've read on the website what a closed-loop is, but is that what the 3 1" holes are for? <<Is my opinion, yes>> I thought that a closed-loop was something that goes all around the inside perimeter of the tank. Blah! <<Is but one way to do it>> Thank you for all your wisdom and your sense of humor...and your long distance help. lol Linda in GA <<Always welcome, Linda. I've listed some links here for you (and your fish guy!) to peruse if you haven't seen them already. Cheers, Eric Russell>> http://www.wetwebmedia.com/plumbingmarart.htm http://www.wetwebmedia.com/pbh2oret.htm http://www.wetwebmedia.com/marsetupgear.htm http://www.wetwebmedia.com/marphysf.htm http://www.wetwebmedia.com/ca/volume_2/cav2i5/Filtration/Filtration.htm http://www.wetwebmedia.com/marfiltdesf.htm http://www.wetwebmedia.com/cllooppbfaqs.htm

R2: New Reef Tank Build'¦Holes In The Bottom Or the Sides? -- 03/08/08 If I order a new 90 gal tank to be drilled, where would you suggest, in your "honorable" opinion, the holes be drilled and what size holes and how many for a 1300gph pump and for cryin' out loud, lol, which hole would be the drain and which ones would be the return? (Now I know you realize I am a southern blonde!) Thank you...Linda <<Ha!... A pair of 1.5' bulkheads for the drains, and a 1' bulkhead for the return, all drilled/mounted on either a side or back panel. EricR>>

R3: New Reef Tank Build'¦Holes In The Bottom Or the Sides? -- 03/08/08 Been reading WetWebMedia.com today at work (that is what I do when it's slow) <<Ah'¦even though I gave up cigarettes back in '85, I tend to take a 'smoke-break' or two during the day to try to keep up with queries as my evening/weekend time is pretty much all-consumed with a large home renovation project at the moment>> ...I came across something you had said to someone a few years back about the siphon overflows and then I remember you telling me when I had my undrilled tank...you had said "using a pair of these devices for redundancy should one fail can work quite well (the trick is to maximize the flow rate as if you had only one overflow device installed." <<Ah yes! This is quite true>> Okay...with a wet/dry/sump with only one drain pipe connection, you could drill another hole into the wet/dry having two connections for the two individual siphon overflows, correct? <<Yes indeed>> Would you hang the boxes side by side on the tank or place one on each side of the tank? <<Whatever is most convenient/fits most easily>> So, on a 90 gal with two CS90 siphon overflow boxes draining into a size 200 wet/dry, using 1" PVC for return, what would the maximum size pump be that could be used? <<Mmm, for 'any' 1' drain'¦maximum 300gph>> Also, my little fish guy says he will fill up my new drilled tank with cycled water...it happens to be the water that he drains out of his client's tank on his maintenance route! Isn't that taking a risk on my new tank getting someone else's cooties? Hahahaha <<Not really'¦at least not any more so than introducing rock/corals/fish'¦even sand, that hasn't been through a quarantine process>> Granted, it would save me a lot of time and some cash making my own water and waiting on it to cycle, but I know it sure would be less risky. <<The tank will likely have 'some' kind of cycle'¦and letting it sit/run fallow for six weeks or so will only make it better, anyway'¦as well as reduce the risk of 'cooties' [grin]>> Always great talking to you. <<Likewise!>> It's going to get cold tomorrow...start your fireplace back up! Linda <<Was a bit chilly today (mid-fifties)'¦but hardly fireplace weather! (Think summer!). EricR>> R4: New Reef Tank Build'¦Holes In The Bottom Or the Sides? -- 03/09/08 Okay...gonna put you on the spot and ask you, your most humble opinion... which one do you favor most/is safest from catastrophe? A bottom drilled tank with built in corner overflow OR a couple of CS90 overflow boxes? Linda <<Mmm, if done properly, the bottom-drilled tank...in my 'most humble' opinion. But honestly, Linda'¦if you are more comfortable with the familiarity of the siphon overflow, a 'duplex' setup re may be the best way for 'you' to go. Cheers my friend, EricR>>

R5: New Reef Tank Build'¦Holes In The Bottom Or the Sides? - 03/09/08 Okie dokie! I think that would be easy enough to order thanks to those specific directions...much appreciated and thank you <<Quite welcome>> ...hope you have been able to dodge the flu <<So far!>> ...I've been lucky enough, so far...(knock on wood or my hard head!) <<Hee-hee!>> Over and out! <<Roger-wilko'¦EricR>>

R6: New Reef Tank Build'¦Holes In The Bottom Or the Sides? -- 03/10/08 Hey Eric, <<Hey Linda!>> I'm sorry; I didn't realize I was leaving out some important info when I mentioned "basic bottom-drilled built in corner overflow' <<Ah, yes'¦the more 'detail' the better>> I meant "basic" meaning the ones that are pre-manufactured with the one 1" drilled hole and one 3/4" drilled hole. <<I see'¦ And your 'fish guy' stated this would handle 1200gph? I must disagree'¦ Flow to a 1' gravity drain should be limited to 300gph to prevent noise issues and possible dangerous siphon conditions. If he is plumbing Mag-12 return pumps on these systems, either there is much headloss thus 'greatly' reducing the perceived flow'¦or the fore mentioned 'siphon' conditions exist (you did state one of the systems you had seen was very noisy)>> With these drilled tanks, my little fish guy usually drills a larger drain hole into the side or top of the sump and also drills a hole on the return side of the sump for an external pump. Sounds, by what you've just told me, that a larger drain hole needs to be drilled in the tank itself, not necessarily the drain hole in the sump. Or both. <<Larger in BOTH, yes'¦as the diameter of the drain line needs to match (or be bigger than) the diameter of the bulkhead. It does no good to simply put a larger diameter drain line on a too-small bulkhead>> I know he would replace anything he broke. <<If he is operating as a 'business' then hopefully he has insurance to cover possible damages to your home as well?>> He knows more than I do about plumbing, but he's learned only in the past year because he doesn't get "out there" enough to see all the possibilities and get ideas from others in the reef business. I don't have a lot of faith in his knowledge...there are no pros here in this area until you get to Atlanta, as said before. <<Mmm yes, well'¦experience 'is' a wonderful teacher'¦and the NET is full of 'ideas' that can be found through diligent keyword searches>> I think that is why I went with the siphon hang-on overflow box on my last 90gal undrilled tank was because that seems to be the going thing in middle GA. <<Or maybe all that was offered by the retailers>> But, go to Atlanta, and they are like, "well, yeah...drilled is the only way to go." <<A deeper/broader base of experience/exchanging of ideas. Perhaps you need to start a reef club out there in 'middle GA' [grin]>> But, they don't come down to middle GA to hook a customer up. Ya know? <<Ya just need to wave enough 'green' [big-grin]>> If I lived in Atlanta, I would have it made. (Burns me up that we ended up here. I was born and raised in Atlanta with all the neat stuff.) <<There does seem to be a very large/strong reef hobby contingent there'¦and some very nice aquatic stores too, so I'm told>> Anyway, I need pictures in order to understand what I am doing, so I do appreciate those websites with the pictures you sent me, which I will definitely share with my little fish guy. <<Ah yes'¦please do>> I am so much a visual person that I am sure that if I could see more pictures of drilled tanks with their simple plumbing, it would all make sense. <<Am sure it would>> I've been to Atlanta to two popular fish stores and none of them have any sample tanks running in the store showing plumbing and drilled holes in the tanks. <<Mmm, yes'¦I'm sure floor space is too 'dear' for such. Now, if you could find a store that does installs and has a work room where they drill/pre-assemble the tanks'¦>> They have all their coral propagation tanks going and the usual fish store systems, but nothing a customer can look at and study and learn from as far as plumbing ideas. <<Not so! Even studying these systems (if the store will allow the access) can provide valuable insights to tank plumbing/fluid-dynamics>> I guess what would be a great idea is to find some kind of club and maybe I could get a look at some club member's tanks. <<Ah yes! Or, as mentioned'¦start one yourself!>> The other store used to have lots of tanks running in their store, but they have really downsized and moved to such a small location that they don't have any tanks running at all, other than the ones they are selling fish out of. Nothing to look at and go, "Oh, so that's how it's supposed to be plumbed!" Anyway, I'm just chatting about nothing now, so I won't hold you up any longer. <<No worries'¦always good to hear from you>> Bye-bye for now...Linda <<Be chatting'¦Eric Russell>>

R7: New Reef Tank Build'¦Holes In The Bottom Or the Sides? -- 03/10/08 Oh my! <<?>> I know you will be glad when all the renovating is done and over. <<Indeed'¦has been non-stop since last October'¦but is worth it/will be very nice once I get it completed>> That can be fun and exciting, but also very exasperating...time goes by very slow during a renovation, it seems. <<So true'¦ And though I'm not 'killing myself' to get it done, it does seem all I do is 'work''¦and I'm sure my wife would have fired me by now if I didn't come so 'cheap.' [grin]>> Thank you for your answers below. <<Hope they helped>> I do believe I can do this project. <<Yay!>> Am still planning on using the 1300 gph external pump for my tank: If I get the holes drilled on the back side of the tank, I've read on Wet Web the placement of the 1.5" holes would be drilled approx. 2" from the corner and 2" from the top of the tank <<Yes'¦ There are others who will say differently, but in my opinion, a good rule of thumb is to leave as much space/glass between holes, and from perimeter edges, as is the 'diameter' of the hole. As an example'¦a 1.5' bulkhead requires a 2 3/8' hole (this may vary slightly depending on manufacturer), this means you would want to keep at least 2 3/8' of glass between the edges of the hole and the perimeter of the tank panels, as well as between any additional holes. Following this 'rule' ensures adequate strength, or mass, around the hole to help prevent stress fractures>> Would I drill the first one 2" from the top and corner of the tank and then the second 1.5" drilled about 4" from the corner and 2" from the top? (or 2" from the 1st one, side by side or one on top of the other? Don't want to weaken the tank by the wrong placement.) <<The second hole can be placed the same distance from the top of the tank as the first, but make its horizontal position based on the measurement from the edge of the first hole (keeping in mind its distance from any panel edges as well)>> Where would that 3rd 1" hole go or could I just as you had once suggested just have the return PVC going up over into the tank? <<You can drill for the return on whichever panel you wish the water to come back through to the tank; but do keep it near the top to preclude having to use a check-valve to prevent draining the tank during a power outage. Or, yes, simply plumb/position the return line 'over the top' of the tank>> The overflow - I was just under the impression the correct size overflow would be installed by the people I order the tank from, matching the size tank...example: this specific size overflow goes in a 90 gal., this specific size goes in a 75, etc. If not, what size overflow would you suggest I order to go in my 90gal drilled tank, "purty" please? <<If you order the tank drilled, then yes, the company should provide the correct sized overflow for the bulkhead installed>> I am assuming the PVC would all be 1"? <<As stated, the drain lines must be 'at least' as large as the bulkheads (i.e. -- 1.5' bulkhead = 1.5' PVC and fittings)>> With these answers, I know I have a good start and the rest I can play with. <<Indeed'¦ Take your time to learn/become comfortable'¦no need to rush in to this>> Getting the tank drilled correctly with the correct size holes and the correct size overflow will be a good beginning. <<Agreed>> I cannot tell you how much I appreciate you and the website. <<Is good to hear/ know>> I will keep in touch and promise to try to keep things down to direct questions instead of running off into so many directions. That must be hard to keep up with. Lol <<Really, not a problem'¦ It is important for you to understand what is going on as a wrong decision here will haunt you later>> Take care...much appreciation! Linda <<Good luck! Keep me posted, EricR>>

R8: New Reef Tank Build'¦Holes In The Bottom Or the Sides? -- 03/11/08 Hey Eric - hahahaha you are SO right...I never thought to offer enough "green" to get those guys down here. Just 1-1/2 hrs south of Atlanta. <<Ah yes! A store owner friend of mine here in Columbia travels all over the state to do 'installs'>> That is a great thought...I never bothered to even ask them. Next time I hit Hotlanta, I know just the store to go to...they are awesome guys. <<You might even want to ask/price-out the cost of having them order and 'pre-build' the tank, versus just having them come out to drill/install a tank you bought elsewhere. You may find the difference in cost; once all totaled, to be negligible, and buying the tank/fittings from them should 'grease the wheels' a bit as far as getting them out to your place>> Most of the time, I am in Atlanta to visit relatives...next time will be to just spend time at the store and talk. <<Always enjoyable'¦to me anyway>> I am going to take my time with this next project and do it right. <<Patience is definitely a virtue here>> Planning on keeping this next tank a very long time. No need in being in a big hurry..."only good things come to those who wait"...I have definitely learned to be patient with this hobby. Tis a very rewarding hobby. <<Indeed! Especially so when approached with the correct mind-set/expectation'¦and not to mention, months of reading and researching [grin]>> I enjoy the work it involves. <<Me too!>> (My husband shakes his head in wonder!) lol <<As does my wife!>> I've forwarded your website to my little fish guy along with the info you have provided. <<Very good>> I think he will really appreciate having this website to learn from. <<We do hope so>> Take care and all the best to you and your family. Linda <<And to you and yours, my friend. Keep me posted on your progress. Good luck! Eric Russell>>

Question about tank integrity re: drilling -- 1/28/08 Dear Crew, <Brian> Hope all is well with you fine ladies and gentlemen. Once again, I find myself seeking the advice of the sea water sages. I know a few of you have prior tank building / fabricating experience, and wanted to run this by those who may have more experience than myself. I've drilled the back panel of my 75 gallon, which I believe is 3/8 inch glass, in preparation for the overflows to the sump, and intake and outputs for the closed loops. 6 holes in total, 5 are to accommodate 1.25 inch bulkheads, and one for a 1.5 inch bulkhead. <Okay> My question is re the integrity of the panel once filled with water. I understand people drill their tanks all the time, and even I admit that the process was much easier than I thought it would be. However, I read many threads on various forums with people stating their tanks have failed usually with cracks radiating from near the location of the holes. I am wondering, would it would be advisable to silicone a few pieces of glass length wise to the back panel in order to provide stability, and reinforce the weakened panel? I was thinking of adding three strips to the back of the panel on the long dimension (48"). Will I gain any added stability to the panel by doing this? Or rather, a waste of time? <Mmm, not an idea w/o merit... do look up the term "Euro-bracing" for ideas on how I would approach this> I appreciate your input, and await your advice. Cheers, Brian <Mmm, a few more statements, related... I encourage you to make sure there is no/little stress from the plumbing "hanging" from the through puts (VERY important) and that the bulkheads themselves are well seated (with a smear of Silastic on the inside and outside faces, including on the gaskets) and that these are securely tightened... once again, to distribute the force about their perimeters... Bob Fenner>

Re: Question about tank integrity re: drilling   1/28/08 Bob, <Brian> Thank you for the swift reply. After researching "euro bracing", I've decided that it would indeed be in my best interest to beef up the integrity of the tank. Will take the suggestion to heart, and visit the local plate glass shop for some reinforcing strips. <Ah, good> Also, I wanted to thank you personally, Bob. When I was new to the hobby and wandered into my LFS to purchase a tank and some fish a few years ago, after speaking with me for a few moments, the clerk told me that there was only one piece of equipment I would need to start with. He then proceeded to walk me over to the hobby literature section, pick up a copy of "The Conscientious Marine Aquarist", and advised me to go home and read it over several times, then come back when I was ready to go. To this day, I still find myself referring to it for advice and guidance. Both I, and my reefs inhabitants thank you. <Welcome my friend> Next time you're in Chesapeake Bay country, drop me a line and the beer and crab cakes are on me! <Mmm, yummy!> Kindly, Brian Rinehart

Re: James, flow rates through plumbing, fittings   11/13/07 OK, bottom line is...the calculators are in err, and the manufacturers of the HOB overflows are fibbing about the 600gph flow rate. Also, when you say the only way you would get that flow rate is by siphoning. Isn't that what the HOB's are actually doing with the "U" tubes? <Yes! Again... much more water to be had via siphoning... but the downsides of... what happens if the siphon/s stop? The issue of transit volume...> Anyway, I must find a more reliable source for calculating such. So goes answering plumbing queries for now.. do not want to look like an ass doing so, for sure. James <The construction, presentation of such "tables", inherent difficulties in explaining their limitations to users is why I/we've chosen not to even present such... You and I can only guess the number of wet floors, shorted electrics, dead livestock... frustration and consternation of hobbyists from such "data". Cheers, BobF>

Re: James, flow rates through plumbing, fittings   11/13/07 OK, I see I have a message in my inbox from the querior. I think I'll tell him my wife is answering this because I passed away yesterday. <Heee! You can only use this one time...> In looking at plumbing calculations on the web, I do see there is much involved, one notably is friction. <Yes... induced drag is a huge factor... I have seen systems where the latitudinal "runs" from lines in the backs of large tanks were very long... there was/is NO way that water was going to get magically "sucked" down these...> Depending on the product being used, <?> friction can decrease flow rates of course. So now I'm thinking the ribbed hose connecting from bulkhead to bulkhead would rank high on the list because of all the ribs present, but probably no where near as bad as direct plumbing using elbows and such. <Oh! Interesting... Well, not much... inside diameter is inside diameter... the ribbing is outside this measure> This job is going to drive me nuts. Have a good day. James (I too, take blood pressure medication, Ziac. I thought this was suppose to be a relaxing hobby. <I use (don't laugh) black flaxseed and 10 mg. of Norvasc daily... Cheers, BobF>

Overflow rates... again.  11/13/07 My flow meter data shows a 1" bulkhead flowing right at 300 gph in a best case scenario. With much plumbing it was more in the neighborhood of 270-280. I used to think they flowed more too!! I plan on confirming the flow meter rates with time vs. volume displaced tests. I will write these up and sent it to you this weekend. Talk soon, Scott V. <Thank you for this input Scott... Am STILL dreaming of that "Aquarium Engineering" book by you and Eric Russell... and I know just the excellent editor that should oversee this project. Am cc'ing James Lawrence (Microcosm) here. James... it's way past time for an update, bettered tome than Pete Escobar's on the topic... What say you? I will gladly help with review of lighting, aquarium and stand, electrical, plumbing... sections. BobF>

Plumbing Nightmare'¦ (Indeed!) -- 12/07/07 Dear Mr. Fenner, <<Hiya Jerry...EricR with you today...>> Why is it the more I read on your website, the more money it costs me to fix the errors!! Yes I know shoulda, woulda, coulda!! <<Ah yes! But think of all the learning experiences/opportunities that have come from it>> I upgraded my tank 4 months ago and was so excited about the upgrade I didn't really check the stats on the overflow. <<Uh-oh...I sense a 'Mega' mistake coming>> Right now I have a 90g reef with a MegaFlow unit, <<Yes, well...try not to giggle when you say that [grin]>> 1' Drain Pipe and ¾' return, which now seems fairly small. <<Mmm, yes...and as Tom Hanks stated when the 'Wonders' fell apart after a single hit song...'A very common tale.' We are well aware of/often hear about these tanks and their shortcomings re the advertised 'Mega' throughputs>> The drain pipe drops into a sump w/ trickle plate/Poly-Filter, bio-balls replaced with DSB/live rock, no lights. <<Okay>> Second chamber holds my AquaC Urchin-Pro and a Rio that pumps into a 20g refugium, from there it returns via a 2400 Mag-Drive, reduced to ¾'. <<Okay...a couple red flags here. First- Pumping from the wet-dry to the refugium and the pumping from the refugium to the tank is just a plain bad idea... Even if you use valves to balance flow/were to use identical pumps, this 'balancing act' just doesn't work due to variable differences in head pressure/line resistance from the buildup of bio-matter. Sooner or later an imbalance 'will occur' likely resulting in water on the floor, damaged equipment, even the possibility of fire or electrocution. You really need to position the wet-dry such that a 'gravity' overflow of sufficient size will supply water to the refugium for return to the display. Second- That 1' drain is only going to handle about 300gph. Assuming zero headloss for the moment from the Mag-Drive, that pump is twelve-times more pump than you need! And no doubt these issues have something to do with you writing in...[grin]>> The problem is a few-fold!! <<Yes>> You state in your plumbing article that you should never pump one box to the next, and that it is destined for disaster. <<Indeed>> Trust me I have spent countless nights wondering when one pump will go out, and because of one bad pump loss two. (and the constant adjustments!!) <<Yep...Murphy's Law 'will' catch up to you>> Also you state that Skimmer and refugium should get raw water, <<Ideally>> and flow through the refugium should be handfuls. <<Hmm...this, in 'my' opinion, is variable...and often dependent on the type of refugium methodology employed. But for the most part, yes, a circulation of a couple to few volumes of water per hour will usually suit>> Here is my plan; since I just bought a new AquaMedic Ozonizer (got a great deal or I would have bought the Sanders) and I am waiting for my ORP controller and new EV120. I figure since I have to make changes anyways, I might as well make them all. <<Excellent>> Promise I am getting to the question!! <<No worries...does help me to have all the info/know the background>> Since drilling is not an option and a hang on back overflow will not fit, here is my new plan. <<So, limited to the existing throughputs, eh'¦you can 'make do' re circulation to the sump/refugium'¦but you will definitely need to provide some supplemental water flow within the tank via powerheads>> I was thinking of taking the return line and making it into a second overflow, since you say it is better to have two than one. <<Some redundancy is good, indeed'¦but this is most often done with these so-called Mega-Flow tanks simply because the supplied throughputs are just too inadequate>> The 1' dropping into the sump (DSB/Live rock will be removed and put into the refugium with the other), the EV-120 in the fist chamber with raw water and the second chamber will hold both pumps. <<Let me stop you right here for a moment'¦ 'Both pumps?!' Even with utilizing both the 1' and ¾' throughputs as drains, you are still only looking at a maximum 'gravity' flow rate of about 450-500 gph'¦ You only need a pump that will supply from 700-900 gph; to allow for head-loss and gradual loss of flow from bio-film buildup in the plumbing. Also, do be sure to plumb a gate-valve 'after' the pump to allow you to throttle-back this flow if/as needed>> Mag 2400 will be piped 1' (or ¾' what do you think is better?) <<I think a smaller pump 'is better''¦with no need to exceed the diameter of the pipe beyond that of the pump outlet>> behind the tank, dropping in by split Loc-lines. <<You will likely find that only a single return will supply enough 'force' with the limited water flow to be useful>> I figure with 4 elbows and 4' of upward pump, collective maybe 9' of headspace. Mag 2400 will now return maybe 1250gph. <<Maybe so'¦but still way more than your drains can handle>> The ¾' will drain into the refugium, so now both skimmer and refugium will get raw water. <<This is good'¦and hopefully the refugium then 'gravity drains' to the pump chamber of the sump>> Rio 1400 returns to a ¾' SeaSwirl. <<Save your money here'¦you just don't have the overflow/drain capacity for it>> Whew!! I was thinking that this addresses all the issues that you have written about. <<But unless I have grossly misunderstood or something has been misstated, your resolutions are flawed>> But then I was thinking, will the overflow wall allow enough water in or will it suck dry? <<The 'overflow wall' will not be an issue, the drains will simply not handle this much water volume>> You say gravity is something you can rely on, so since I am pumping more back in, won't the overflow box fill just as fast? <<The box will fill, yes, and overflow'¦ And gravity is indeed the issue here. Because you can pump a certain volume of water through a specified diameter of pipe does not mean that same volume will 'gravity drain' through the same diameter'¦is not the same hydrodynamics. You can not drain the volume of water from this tank that you are indicating without increasing the number or size of the throughputs. Since you say this is not possible, your only option is to reduce the volume of water returned to the tank>> And if the box is overwhelmed with how much I am pulling out, is there a way to speed up the amount flowing in? Maybe cut bigger and deeper grooves on the top? <<Again'¦I think the overflow box is the least of your concerns here>> Well anyways before I start ripping things out and buying new parts I thought I would run this past you. <<I'm very glad you did>> Your views and suggestions would be greatly appreciated. Since you started this whole thing anyways!! I would have been perfectly fine sitting in ignorance!! <<Mmm'¦not for long'¦>> Have an awesome night and if I haven't said it yet, you guys are the absolute best on the web and anywhere else!! <<Thank you'¦a collective effort>> Thanks, Jerry <<Jerry'¦ Please write me back to let me know your thoughts/understanding of what I have stated, along with anything you have already done and the results re (have you run this tank lately?). I do think this matter likely bears further discussion. Regards, Eric Russell>>

Re: New Tank And How... less/more on through puts, flow rates...  12/4/07 They designed it all I have 2 x 1 inch drains with elbows. I have 2 x Aqua Euro return pumps with 1200 to 1400gph each so 2400 to 2800 return. They say 1inch drain should handle 1200gph. Is this not true? <Well, lets put it this way, I'm running a Little Giant circulation pump that puts out about 1000gph with my three foot head, have no elbows in my drain line, and I have to throttle the pump down about 20%. I'd ask Tenecor if they tried the system out before they sent it out to you. I might ask one question...are the drains tied together into a "T"?. James (Salty Dog)> <<Mmmm, ummm, none of the above... the one inch lines in an ideal universe can/will handle no more than about 300 gph... unless they're (dangerously) operating as siphons... Time to read... and consider adding more holes/drain lines or routing out the present ones to at least 1 1/2" ID fittings... Start here (both James and the querier):  http://wetwebmedia.com/marsetupindex2.htm The fourth (pink) tray down. RMF>>

85 gallon hex mixed reef - should I continue? Drilling holes mostly   7/27/07 Hello to all, <Hi there> I've been searching here (great info!) and various other sites for awhile now, and can't find many relevant posts to confirm my plan before I continue. I'll try to describe my overall plan and then ask for your thoughts on a few specifics. <Okay> I picked up a used 85 gal (Oceanic?) hex glass tank (~16" each side x 30" deep) and stand a few years back on the cheap with the intent of a mixed reef tank. Original plans were for a unique viewable-on-all-sides design with centrally located overflow/return to a remote sump. A custom central (probably circular) <Consider sleeving this... to move water from the lower level...> overflow will be at the top surface with water draining down two 1" Durso pipes <Mmm, too small... make this one two inch...> to a remote sump. The sump will have standard refugium, skimmer, Kalk drip, external return pump, etc. The return will flow up from the bottom of the tank, 180 back down into the middle (with a siphon break hole) <Mmmm> then split to multiple outlets along the depth of the tank. The tank is to have a 4-6" DSB with LR stacked/attached in a cone shape mostly full-height to the vertical drain/return pipes up to the bottom of the overflow. I know hex tanks don't offer ideal surface area, but hope the sump/skimmer will mitigate this. <Unless power, circulation fail...> Shooting for 20-30x turnover so I can handle some SPS at the upper level and Softies down lower and just a few small fish with a single 250W MH and supplemental 24" T5's. First problem - Without adequate research beforehand, I had three holes drilled for 1" bulkhead fittings in the center of the tank (two for drains, one for return). My hope was to supply all the tank flow requirements through these, but checking some of the calculators looks like the most I can get is about 1700 gpm (with 26" of overflow length - maybe a custom 8" dia overflow). <Not even close to this...> Any thoughts on maximizing flow with this setup or any visually unobtrusive powerheads to make up the difference? <I'd start again... have the tank re-drilled> Second problem - Being an older tank, I plan to reseal all the joints. <I'd reconsider this... a big job to cut away, clean all, separate the glass... likely the re-do will be less secure than the present... Cheaper by far time-wise to just buy a new tank...> Before I go through the hassle of resealing, do you think the three holes in the center of the bottom have compromised the strength too much to handle the weight of water/rock/sand (the ligaments between the holes are ~2", the bottom is 24" wide face-to-face)? Would laying a piece of ½-3/4" HDPE on the bottom prior to stacking help out? <Maybe... better to repair/seal a piece of glass over all, inside and one outside... and start again as stated...> Thanks for all your valuable information already posted & any comments on these two issues and any other insights is greatly appreciated. Regards, Michael Johnson <I do wish we had chatted afore... Please think this project over for a week or so... before doing much else. Bob Fenner>

Need help with a tank stand--can't tighten bottom bulkheads due to wood center brace  6/20/07 Hi there, I'm hoping you can help me. I have a Perfecto 150-gallon glass aquarium whose dimensions are: 48" long, 24" wide and 30" tall. The tank has plastic center braces on the top and bottom. The stand for the tank is wood and supports it fully around all edges; the top is fully open but with a wood center brace running vertically through the center. Recently I had the tank sent out to an aquarium company to have the glass bottom drilled for two bulkheads along with an internal overflow box installed. I just got the tank back today, and they did a beautiful job. However, when the tank was set back on its stand, the wood center brace on the stand was too wide to allow me to fully tighten the bulkheads underneath. <Doh!> I asked the company who did the work what I could do to rectify this--they said I could notch a cutout in either side of the wood center brace to accommodate the bulkhead fittings. <Mmmm> However, I'm worried that this will compromise the integrity of the stand-- <Yes> I don't want it collapsing and spilling 150 gallons of water on the floor. Could you guys help me out as to what I should do--should I consult with an engineer first or is it okay to do this modification? Any advice would be greatly appreciated. Thank you. <Well... likely a "thinner" nut can be found... or the through-hull/bulkhead fitting reversed (with the throat up, perhaps shaved, cut down...) and an extra gasket found for both sides... and a smear of Silastic on both sides... that will do here... Perhaps with some shaving of the wood twixt the tank and stand to accommodate... If push comes to proverbial shove, you might need to consider adhering the (likely PVC) fitting directly onto the tanks glass... and dedicating yourself to never jarring it... Otherwise, the worst... giving up on the present holes, sealing over them (with glass panel/s and Silastic) and having the tank re-drilled. I agree with your NOT cutting through the manufactured stand support... UNLESS you feel comfortable (YOU!) with replacing this support (and losing the manufacturer's warrantee) with two new ones, placed on either side... Which is really what I'd do... Cheers, BobF>

Re: Need help with a tank stand--can't tighten bottom bulkheads due to wood center brace   6/21/07 Wow! Thanks so much, Bob, for your kind reply!! I really loved your book, by the way; it really helped me get started with my tank! Plus I've learned so much by reading through all the articles and FAQ's from WetWeb Media; you guys are great! I think I've come up with a plan for my stand. I'd really rather not mess around with the bulkheads; I only really need to notch the wood 1/4" on either side, but leave the center brace in place, and I think I'll place two new boards on either side, like you advised. I really don't want to have the tank re-drilled: it took the company forever to get the work done; I'd consider getting a new stand before doing that. Anyway, thank you so much, Bob, you've really helped me out! <Ah, good! Cheers, BobF>

Request for Enlightenment from the Crew -- 06/14/07 Hello Crew: <Uhh, Dan> First and foremost thank you so much for this website. The information here is fantastic, I can't stop reading and my wife is getting irritated because I'm spending most of my evenings at WWM. <Heeeeeee! That's not "on", but "at"! Wow!> I keep telling her that at least it's better than the local bar! <And cheaper and easier on your liver!> Anyway here goes, I just purchased a 100-gallon rectangular tank (60'x18x24) and requested that the internal overflow be placed in the back left corner of the tank. When the tank arrived I noticed that the overflow drain hole could only accommodate a single 1' bulkhead (hole size is 1.75'). <Bunk!> The LFS is recommending a Mag 12 that will have to pump a little less than 5' high and I plan on splitting the return so that the returns are from each side of the corner overflow. I'm guessing that the flow rate will be around 1,000 gph. From what I read on your site that a 1' overflow can handle 600 gph maximum and is better at 300 gph, <This last is likely the maximum... You need larger holeS... plural> I brought this to the attention of the LFS. They told me that they have used this set up before and it will be fine. <Mmm, no. They're wrong or at least not understanding... or maybe I'm a butterfly dreaming I'm a human pet-fish kind of guy not understanding... and will wake up and be a real Reef Ready marine system... Wait, no... I AM a pet-fish kind of guy and am just confusing the situation. They're wrong> (Their other solution is to install a smaller pump, <Uhh, Dan... no> which I do not think is a viable due to the very low turnover rate that would be required.) They have also recommended 2 Tek retro fit T5s (4 bulbs), a Euro Reef RS135 and a 40 gallon sump. Your wisdom please! <Nyuk nyuk, nyuk. Wise guy eh?> Thanks, Dan W. - California <I'd go with this skimmer... keep looking around for the lights... have someone from the shop come out and drill two 2 1/2 " OD holes for use here (one over the existing if you'd like) and not both at the same level necessarily... And read here: http://www.wetwebmedia.com/marsetupindex2.htm "That'll be very... time consuming"... Mr. Deets in "Beetlejuice". BobF>

Moving sump to basement, Increasing Bulkhead Size/Plumbing a Skimmer and Chiller - 04/15/07 Hello Crew, <<Hi Jerry>> Thanks for your help in the past on lighting, now I could use your help on planning plumbing. <<Let's see what we can do>> I want to move my sump, skimmer and pump (and new chiller) in the basement. <<Ok>> It would run through wall with 2x4 studs and 2x4 plates which limits pipes to 1.5 or less.  My current 110 acrylic reef tank has overflow 1" and 3/4 return with Little Giant 4 pump.  Can the 1" be enlarged with Roto-Zip or Dremel tool or a file to accommodate a 2" bulkhead? <<It can (using the Roto/Dremel tool), or even with an appropriately sized hole saw like those meant for cutting holes in wood (the "bi-metal" blades work the best IMO)>> Will the 3/4 return be enough for GenX Mak 4 (1200gph) after 12' lift and split for chiller and skimmer? <<It will, though I would increase this to 1", since you're re-cutting new holes anyway.  Also, I don't recommend "splitting" the pump to feed the skimmer and chiller.  This sort of "balancing act" just doesn't work.  It's not so much an issue with the chiller, but you will find yourself having to constantly fiddle with the skimmer to keep it "tuned" due to the almost constant variations in flow because of fluctuating fluid dynamics'¦best to use a dedicated pump for the skimmer in my opinion>> Would you recommend turning both bulkheads into overflow to sump and return over the tank? <<Since the sump will be located remote from the display/out of the living area and if your intent is to maximize flow through the sump to reduce the need for ancillary water flow devices...absolutely>> Thanks so much, Jerry <<Happy to assist.  EricR>>

Bulkhead Location - 04/11/07 Hello, <<Greetings>> I wrote to you about two years ago when I was planning to set up my Mediterranean aquarium (I'm in Italy).  You were very helpful and I'm happy to say that my tank looks great and is very healthy on its second birthday! <<Ah...very nice to know>> I am now planning to replace it with a larger aquarium which a glazier is going to cut and silicone for me.  The measurements are (in inches) 36 long by 16 wide by 20 tall.  It will have a DSB and a Remora backpack skimmer which I plan to place in the sump (bucket). <<I see>> My questions are these:  does drilling a one-inch hole in the back of the tank compromise the strength of the aquarium more than if the hole were drilled on the side? <<Not at all...the 'compromise,' if any, would come from its placement in regards to the edges/seals of the tank>> Does it make any difference if the hole is in a corner or in the center? <<Either is suitable...as long as sufficient distance is maintained from the edges of the panels.  A good rule of thumb in my opinion is to drill the holes such that, the edges of the hole are no closer to the edges of the panel, than a distance equal to the diameter of the hole...so the bigger the hole, the greater the distance.  In other words...if you drill a 1 7/8' diameter hole for a 1' bulkhead fitting, the edges of the hole would be at least 1 7/8' from the nearest panel edge>> In your opinion, is it better to make the hole close to the waterline with a horizontal tube and basket or make the hole lower down in the aquarium and connect an "L" tube which can be adjusted for height to achieve the desired water level? <<Again either is suitable (I use the latter method on my tank)...as long as you maintain sufficient distance from the panel edge when drilling the hole>> There will be only one hole for the overflow and the return will be over the top edge with a closed loop manifold (thanks for such a great idea!).  My husband is much less enthusiastic than I am about aquariums so I'm only getting one chance to plan and build this tank correctly...since this is not an overflow device used by any of my Med-forum friends, I wanted to check with you to reassure myself that I'm making intelligent choices. <<Understood>> Thanks so much for your help and your amazing website! Eileen <<Is our pleasure to share.  Eric Russell>>

Pump question for Aquavim tank... Not Reef Ready- 03/25/07 Hello guys! I recently purchased an Aquavim 88 gallon seamless RR < http://www.aquavim.com/ rounded glass...> tank setup.  It's an awesome attention-getter in my living room, but I'm getting frustrated trying to figure out a circulation/pump plan for this very tall tank/stand.  I'm calculating a head pressure of about 5.5 feet.(4.5 feet from sump to top of overflow box, then a 90 degree turn, then a 45 degree turn into tank).  It has a single 1" outflow, then a 3/4" return. (I know, the 1" return is killing me!)   <As will the 3/4" return... Not RR... Reef Ready> It seems like I'm in between pump sizes for my planned FOWLR setup with Orca sump refuge.  For example, the mag 7 puts me around 400-420 gph which is 4.6 turnovers. <The 1" return may not fit this...> Moreover, the mag 7 only has a 1/2" outlet so I would lose even more head pressure going up to a 3/4" return. <Not much... I wouldn't be concerned here> The Mag 9.5 would be around 720-750. (Too much for a 1" return). <Way>    The pump has to be the submersible type as I don't have a bulkhead for the return. <I'd cut, fit one... or switch sumps to this...> I could go with a mag 7 and do powerheads in-tank, but this is ugly amongst the other issues.  Could I valve-down a Mag 9.5?? <Could...> Is this safe?? <Is, but I wouldn't...>   What would you do?? <Try to see what sort of flow you can get through both the present through-puts... and loop the discharge, return from whatever pump you settle on to over the top... on/with some sort of "closed loop" arrangement... this pre-drilled tank is not really able to be used for the intended purpose...> Any other pump brand or suggestions that would get me closer to 500 gph without having to deal with valves?? Thanks guys!! Kris K <As stated... and posted. Read here: http://www.wetwebmedia.com/marsetupindex2.htm It's... an education. Bob Fenner>

Drilling a 120-gallon Aquarium on 18" Side   2/14/07 Hi, <Paul> Sorry about the previous blank email; hit the wrong button. <Ahh, another mystery solved> I really enjoy your forum and appreciate the last assistance you provided about the seam on my new aquarium.  I would now like to drill it for overflow and a closed-loop system. (Aughh, not another drilling question)  I am using the aquarium as a room divider so it will be seen on three sides (the two long and one short, obviously, I guess).  So I will only be able to drill on the one short end.  The tank dimensions are 60" X  18" X 24".  The glass is 3/8" thick.  I would like to drill three 2- 3/8" (60 mm) holes to allow for 1.5" bulkheads. <Sounds good>   I want to use 2 of the bulkheads for outlets to the sump and use the third for supplying the closed-loop.  Most recommendations I can find suggest putting the bulkheads as high as possible.  Would 3 of these holes drilled in a row along the upper part of the 18" side be too many? <Should be fine... I'd allow a "couple" of inches of glass above each hole.> I'm concerned about weakening the side too much.  There would be about 2.75" between the holes and 2.75" in from each side.  If this is too many holes, should I just use two holes, one for the return and one for the CL.  Or perhaps two in a row and one a bit lower?   <I would go with the three you list... spaced as you state... Have you given much thought as to how you'll arrange the return discharge/s?> Thanks again and in advance for your help! Paul H. <BobF>

Bulkheads And Flow - 08/07/05 Dear Eric, I promise this is the last time I'll bother you. <<Hello again Andrew...no bother...really...I'm happy to try to assist.>> But I was thinking about it and thought that (2) 1.5" bulkheads would/could give me around 1000gph. (Please correct me if I'm wrong) <<If you're talking about both draining to the sump, then yes, is quite plausible.  Though I must say, that is an awful lot of water to process through a sump on such a small tank (30g)...the slightest restriction is going to put water on the floor in a hurry.  Not to mention the NOISE it is going to make.  I would recommend using one bulkhead to drain to the sump in conjunction with a smaller pump (say a MAG 5), and use the other bulkhead to feed a closed-loop with another MAG 5 or even a MAG 7.>> I was planning on running a Mag Drive MD9.5.  I calculated that this would give me about 800gph at 4.5' head.  Is that to much to run through a sump? <<Ah, should read ahead <G>...>> I wasn't planning on having a large sump, maybe 10-20 gallons and a separate 10 gallon Plenum.  I was planning on running the return into a manifold and was wondering if I should stick with the 1" bulkheads and run a smaller pump and drill a third 1" bulkhead to run closed loop.  I would only do this if I had no other choice about the sump. <<Now you're talkin'...  Here's my recommendation for the simplest, most manageable configuration in my opinion.  Have three holes drilled for 1" bulkheads...Use two bulkheads to drain to the sump with a MAG 7 return pump.  Use the third bulkhead to feed a closed loop with another MAG 7 pump.  With head loss due to height/plumbing, you'll have a total flow rate of around 600-700 gph I'm guessing.  By using "two" 1" overflows you will be able to increase the pump size a bit (MAG 9.5) if you determine you need/want the extra flow.  Also...if given the choice...go with the 20 gallon tank for your sump...you need to ensure you will have enough "empty space" to handle the drain-down from the display tank in the advent of a power outage.>> It will only contain a skimmer, a little mechanical filtration, and a little chemical.  <<and your pumps>>  Will this be overloaded? <<Assuming you go with the larger of the two sump choices (20g), should be fine.>> Thanks Again (and again and again...) Andrew <<My pleasure my friend, EricR>>

Need increased drainage flow to keep up with pump... Small holes really don't 7/7/06 Hi, I just started plumbing a 75g reef-ready tank with a corner overflow and 1" bulkheads drilled on the bottom of the tank. <... need to be bigger, larger diameter...>   The filter I plan on setting up with this tank will be a EcoSystem mud-filter which requires 800 gph to run effectively for a 75g aquarium. <Mmm, could/can be run on less... with other filtration, circulation provided otherwise> The pump I bought is a CA-4000 submersible pump which puts out over 1100 gph at 0' of head and around 800 gph at 3 1/2' of head which is how I have it connected currently.  My problem is that the overflow drain cannot keep up with the pump and the pump begins to pump half air half water after only a few minute of the system being turned on. <Yep> I've researched and found that the max flow through a 1" bulkhead is around 600 gph so most likely that is my problem. <Agreed> Is there any way to increase the drainage flow without drilling a larger hole for a larger bulkhead? <...? Mmm... well, no... you need to either add flow elsewise or re-drill... Please read here: http://www.wetwebmedia.com/pbholesfaqs.htm and the linked files above. Bob Fenner>

Using Old Rock/Drilling Bulkheads - 08/27/06 Hey guys, <<Hello (but don't forget the very capable ladies here as well)>> Thanks again for your time and dedication to our hobby! <<Is an honor/pleasure to help>>   I have 2 issues I need help with: <<Alrighty>> First, I have read thru the LR section in depth and could not find an exact match to my problem.  I recently purchased a used, and neglected 120 gallon that housed a single clown grouper with several large pieces of rock (it was a FO with rock??). <<Indeed...that would be a FOWLR (Fish Only With Live Rock)>> I have kept the rock wet for a few days and can see a few small life forms on it (actual moving little white/clear bug things). <<Amphipods...probably>> The rock looks terrible as the tank was neglected and the rock is all dark brown and black.  I will be setting this tank up as a FOWLR and I am thinking that I would like to start over with the rock.  Letting it dry and cleaning it somehow and then letting it cure in the tank for a month or two before adding new fish (pending testing results). <<Mmm...letting the rock "dry out" will negate its benefits...why not simply keep the rock as it is?  If the color is an issue, it will likely change with improved water quality/lighting>> Can I get the rock to look better? <<Depends on what you consider is "better">> Is it worth losing whatever life it has on it? <<Not in my opinion>> It was not really a traditional live rock, <<...???>> it has life but it looks very bad.  They are great sized pieces.  The substrate is crushed coral, I would like to reuse it.  It also has black and brown staining on it. <<This is most likely forms of algae, and will "change" with changes to the environment, as stated>> Can this also be cleaned?  If so how? <<Swirling/rinsing with clean saltwater will do the least damage, though you will still loose some biota>> I don't mind starting over on the rock but will my cleaning methods effect any future fish or possible changes to inverts/coral down the road if I go that direction? <<Indeed it will...you could give the rock a rinse and a "light" brushing with a soft-bristle brush, or replace it (entirely or in portions) with fresh live rock>> Second, the tank is a traditional (non RR) tank.  It came with a sump/wet-dry and a HOT overflow.  I am weary of the overflow as I hear that they will eventually fail. <<Is a good chance, yes...but this risk can be lessened a great deal by employing a redundant system (two siphon overflow boxes) with the first>> I have once again read on WWM about tank drilling and am thoroughly confused by all the different opinions and issues. <<Let's see if I can help un-confuse you>> I would like to drill the rear for 2 sump supplies and 2 sump returns.  Where exactly (how far down and over/apart) do you recommend? <<Well, if you've established the back glass in non-tempered, I recommend you place the throughputs the width of the hole-to-be-drilled from the edges of the tank, and no closer re to any other throughputs...clear as mud?  For example...a heavy duty 1.5" bulkhead requires a 2.6" hole...the edge of the hole should be no closer than 2.6" from any edge of the tank, or from any edge of another bulkhead hole.  Adjustment of water height in the tank can be accomplished with elbows to raise the level of the pipe outside the tank, or used as adjustable "overflows" within the tank>> Also what size is best for this size tank if I use a strainer for the supplies down and a directional elbow for the return up? <<Two 1.5" bulkheads for the drains, and one or two .75" or 1" bulkheads for the returns...or you can simply plumb the returns over the back/ends of the tank>> Should both the supply and the return have a T installed before the sump? <<For what purpose?...in what configuration?>> Also, are there and tips for drilling? <<Indeed, yes...have a read here:   http://www.wetwebmedia.com/pbholesfaqs.htm >> I have seen a tank drilled before and they used cooking oil for the lubricant while cutting?  Is this OK? <<I've always just used water for lubricating the drill bit...works well and is easy to clean up>> I plan on ordering the needed bits online, any recommended sources? <<Several choices about...I bought my last bit here: http://www.diamond-drill-bit-and-tool.com/Diamond-Drill/MAIN.htm >> Any tips?   <<Heat is your enemy...follow the recommended rotation speed for the size core drill bit used.  The manufacturer states these bits can be used "dry", but use of a lubricant (water) will keep heat down, greatly extend the life of the bit, and speed the drilling process...I use simple 'Play-Dough' to create a "damn" around the area to be drilled and fill/refill with water as needed while drilling.  Also, when possible, use of a drill-press or drill-jig to keep the bit vertical to the glass surface will lessen the chance of damage/fracture of the panel>> Thanks once again for your help and contribution to our obsession!!! Randy <<Quite welcome.  Regards, EricR>>

Pump Size and Overflows Dear Bob and Crew, <Scott F. your Crew member today> How do you guys rate the Mag Drive pumps in  terms of reliability? <I find the new Mag Drive pumps to be quite reliable> I was thinking of getting the MD24 for a 75 gallon with 55 gallon sump. I was hoping 4, 1" bulkheads could handle 1900 gph. Do you think I'll be ok? <I think that they will, <<No... RMF>> but with little margin. You may want to go for 1.5" overflows to be safe. Regards, Scott F> <<Yep... RMF>>

Overflows Hey guys! I have a custom tank in the plans. Its a 125 gallon. Dimensions are 60LX24DX20H. My LFS is having it built and drilled. I do not know much about how big or where to drill so I was relying on them for information. Before I went through it, I wanted to run what they told me to you guys to see what you thought. They recommended that I have 1 drill in the center of the back wall. It will have the wall thing built around it (don't know what it is called, but it has the groves in the top for the water to flow through).  <An overflow "tower" or raceway. Not necessary if drilled through the back... you can use commercially made thread in screens instead> Should the holes be in the back or on the bottom of the tank? <Almost always in the back> This (wall) will have these grooves on three sides. I was wondering if it would be better to have 2 holes drilled, one in each back corner but being in the corner, each would only have 2 sides of the grove things. I would also appreciate an opinion for a pump. I want a good one so I was thinking about Iwaki. but unsure of how much pump I need. Thank you for any information you can shed on my situation.  Rob <Rob, your answers and much other needed input on these matters is archived on our site: www.WetWebMedia.com Go there, use the search tool, or better, peruse the setup area of the marine section. Bob Fenner>

Bulkhead Diameter Hi Guys- <Hey there! Scott F. your guy tonight!> I have just purchased a new pump, Amp Master 3000, and am worried about the necessary size for the return piping to the sump. I currently have one overflow box in the back corner with a 1.125 ID bulkhead (using a Durso standpipe to keep things quiet). In order to handle the 3000 gallons per hour, I am having another overflow box installed in the other back corner, but not sure of the size piping that I need. I am certainly not an engineer, but found some gravity flow equations on the web that gave me an overall minimum ID of about 2" taking into account the 3 foot vertical drop and 3 foot horizontal length to the sump. Does this sound about right to you? <Yep. I'd go with 2 inch standpipes for this type of flow> Therefore, would a 1.5 inch new bulkhead be enough with the current 1.125" in the other corner, or should I go larger? Thanks for all your help, Steve <Larger cannot hurt, but I believe that 2" would be the way to go! Regards, Scott F.> 

- Overflow Size - Hello everyone. <Hello.> I have a quick question. I would have posted in the forum but it appears to be down right now. I have upgraded my pump to a Quiet One 6000 and have put all the pumping into place. I have a 55G tank and a 10G sump. Now I was wondering what size of an overflow would I need? I currently have a H.O.T overflow box with a 1" and 1 1/2" U tubes to move the water between the boxes. I have a 1" drain hose in the back box. I currently have to use a ball valve to throttle back the pump because my drain can not move enough water. My current box is 5" across 7" deep and 3" thick. I was wondering if I increase the drain from 1" to 1 1/2" would that be enough? <Yes, that would make a big difference.> I am currently looking at building an overflow setup that is 15"x8"x4" and using either a 1 1/2" drain or two 1" drains. <Either would be adequate, but you also might to think about two overflow boxes which will give you the right amount of drainage and also redundancy should one of the two develop problems.> I will be using two 1 1/2" U tubes to move the water between the boxes. Could you give me your ideal on how many drains I would need and what size. <Two overflow boxes, each with a 1.5" bulkhead would be perfect.> Oh and the pump will be moving about 943GPH with my current plumping. Thanks. <Cheers, J -- >

- Bulkheads - Hi Guys, I am starting a 180 gal. reef. My two corner overflow are 2". Last time I wrote I was having problems with water draining fast enough. So a added two 1 1/2" bulkhead on the back wall of the tank and two 1". My two pumps equal to 5100 gal. /hr. Now when I turn the pumps on I hear a loud sucking noise from the 2" overflow. Do I still need to add more bulkheads? <No... the sucking sound is just what happens when you have a large amount of water passing through them... air is being pulled down with the water.> I want to avoid dialing back the pumps since water entering the tank goes thru a manifold. My tank is still in the testing stages so I am flexible. Also what is the typical flow rating on these bulk heads? <A one inch fitting should be able to move 1500 GPH peak... reality will be somewhat less. A 1.5" bulkhead should be able to handle about 2500 GPH max.> What would the proper size sump be on a tank this size? <As large as possible - you've got a lot of water in transit and you'll need room to have a working sump and somewhere for the transit volume to go when the power shuts off.> Thanks for you dedication to this site. Sincerely Stephan <Cheers, J -- >

Max drain in a 1.75" bulkhead? Hello to the WWM crew! << Blundell here. >> Although I am sure this info is somewhere in your archives I had no luck locating it so here we go.      My 80 AGA RR has a single bulkhead in the bottom of the overflow box.  The inside of this bulkhead is 1.75" wide and the outside is 2.4" wide. << That is big. >> I need to know the max GPH I can run through this so I don't purchase too large of a pump.  I am currently looking at the sequence Reeflo dart which would run about 2700 gph @ 4 foot head. << I bet it can handle that.  I'd try it out, that is really the only way to know. >> What is the max gph I can swing with this bulkhead?  Should I consider a second closed loop pump on a separate manifold (I currently am running a mak4 (1180 gph) on a squid and my SPS need more flow!). << Extra closed loop systems are great.  Really no reason not to have one.  But I think your drain will keep up. >> Much thanks in advance for all your help!  ~CK~   <<  Blundell  >> <... what if there is some slowing down, occlusion here? I do wish there were more than one drain line... RMF>

- Bulkheads and Pumps - Good morning WWM Crew. I am in the process of planning the filtration/circulation for a 120 gallon salt water tank and would like you opinions on bulkhead/pipe sizes. The tank, as of now, is going to be FOWLR. What I was thinking was a 1" line going to a 29 gallon refugium, a 1" line going to a 16 gallon sump, and a 2" line feeding a closed loop manifold. Could you please advise on this or what you think would be more appropriate along with pump sizes to push all this. <As far as bulkhead sizes go, it all sounds do-able although two inches may be a bit excessive for a closed loop... at the very least make sure you have screens on the input and output sides so no one swims into it when the power is off. As for pumps... you're on your own there. There are many good brands and several sizes of each. Flow rates should be as high as is reasonable... if you could accomplish 10 to 20 times turnover for the system, you'd be doing well. Much more than that and you may be sloshing water out of the tank. However, I suggest you rethink the plumbing of the two one inch lines going to separate boxes... your overflow rate will be constant to both - if you put different sized pumps on each box, the one with the lower flow rate will eventually overflow. Much better, if you want a refugium to fill it directly from your main sump and let it gravity feed back into the main tank or sump.> Thank you very much for your time and knowledge. Troy <Cheers, J -- > Bulkhead sizes Good morning WWM Crew. <Good morrow to you Troy> I am in the process of planning the filtration/circulation for a 120 gallon salt water tank and would like you opinions on bulkhead/pipe sizes. <Okay> The tank, as of now, is going to be FOWLR. What I was thinking was a 1" line going to a 29 gallon refugium, a 1" line going to a 16 gallon sump, and a 2" line feeding a closed loop manifold. Could you please advise on this or what you think would be more appropriate along with pump sizes to push all this. <Mmm, a few things... the drain lines need to be larger... at least 1 1/2" inside diameter... I'd make them 2"... and the discharge/manifold plumbing should be the diameter of the outgoing side of your pump volute, not larger> Thank you very much for your time and knowledge. Troy <You'd likely benefit from reading the marine plumbing article and FAQs posted on WWM. Start here: http://www.wetwebmedia.com/plumbingmarart.htm and on to the linked files (in blue, at top). Bob Fenner>

Drilled hole size and what to do with them. Mr. Fenner,                   First let me say how much I have enjoyed this site. I have learned a great deal but do get confused at times. <I as well> I am in the process of starting up a 150 Gal fish only tank, it has been 8 years since it was last running.                  I read the entire plumbing section and got my tank drilled. I think it may be a bit too much though. I had 4 holes drilled that are 2 3/4 inch for the drains and one 1 3/4 hole for a loop return like you have described. The drains will empty into the basement 10 feet below. The sump is 55 gallon wet dry acrylic. <Some through-puts now!>                 My questions are this........ Should I "cap" 2 of the bulkheads and just use two to return to the sump? <I would, yes... unless you intend to have humongous flow through all four> Should I use all 4 and connect two and two into a "Y" connection, or should I run all 4 to the sump? <Could connect two of two together... but the cost of bulk-heads... I would likely run just two of the four together, and cap the other two> BTW my wet dry has only two one inch holes drilled in the top. I will need to enlarge the holes to fit either 2 or 4 drain lines. <Yes... or retro a drip tray, baffle of some sort to accommodate the flow from above>                 I am shooting for between 750-2000 GPH for flow rate. Did I overkill with the drains {4---- 2" pvc}? <Mmm, yes, but better than under-killing it> Hope this isn't too confusing. I am planning on plumbing to system next week and hope I didn't mess it up.                Sincerely,                                 Jeff Resch <No real problem to cut acrylic or glass and silicone over the other fittings. Bob Fenner> Hole, bulkhead size Hi I just got a 2inch hole drilled in my 135 gallon tank. what size of bulkhead would fit in here. I have a 1 1/2 inch but it doesn't fit. The base on that bulkhead in 2 1/2inches. Can you get a 1 1/2 inch bulkheads with a 2 inch base? hope this makes sense Tristan <Yes to the last statement. Look around... there are "thinner" outside diameter bulkheads (the ones for spas/Jacuzzis for instance) that have 1 1/2" inside diameter and less than 2" outside diameter. Spears makes these... and a few places (try MarineDepot.com) offer them for sale online. Bob Fenner>

Overflows If it were your tank: How many & what size holes would you have drilled on the back wall of the tank (assuming a pump that can handle 3600gph at 6-8ft of head)? <For a 180 gallon, likely six foot tank? Three, one toward each corner and one in the middle... of 1 1/2" inside diameter> I have heard that the reason people do the in-tank overflow is that the water builds up after going over the overflow creating more of a vertical push into the outflow tubes vs. a couple top of the back tank holes which outflow horizontally.  Does that make a substantial difference for flow? <Mmm, am concerned I may not be understanding you here, but the only real difference in such arrangements is the addition of horizontal piping, fittings, rather than more initial vertical drop> If I understand you correctly, it sounds like your advice would be to drill 2-3 holes on the upper back tank walls, use bulkheads & screw in strainers, and then on the outside of the back tank wall, simply connect hard or soft plumbing leading to the sump? <Yes> What distance is advisable for the holes to be drilled from the top of the tank? <Two or four inches in this case/size bulkheads... to either attach screening horizontally or (with the four inch gap) attach threaded elbows... Bob Fenner>

Placement of drilled holes in tank 6/18/05 Hi crew, <Howdy!> Haven't been in touch for a while (6 months or so) <Nor I... with reality. Hoping to return one day... enjoying the view in the meantime :)> but I wish to ask what may seem a fairly straight forward question but one which I seem to be getting several answers. I will try to explain keeping it as short as I can. <Rock on my salty brother>   a.. Briefly:- Ordered new tank 48"X18"X24" high. Asked for two holes (2"each) to be drilled in back panel  near the top. (To go to sump) <Excellent>   b.. One week later received phone call to say they could not do this and had broken two panes of glass trying. <Strange... I have the same sized aquarium with two 2" holes as well as two 1" holes. They must have had poor skills/equipment. No flaw of the tank/size here>   c.. Company asked me if it were ok if they drilled the holes at the bottom of the back panel instead? <Yikes! What's the difference in glass/panes?> I said that would be fine but suggested they drilled the at the bottom and then turned the glass up the other way so the holes were at the top ;-) <Ha! Spot-on my friend!!!>   d.. (I think they were trying to drill it after construction)   e.. Anyway. Received tank with two holes drilled in rear panel RHS one above the other with a weir ! <OK. Are the holes split? That is to say, one above and one below the weir? If so, make the bottom a closed loop manifold intake>   f.. Messed around and got tank working but found the weir was too high and for the water overflow the weir I had to fill the tank until the water touched the cover glasses.....Not good. <Ughhh.>   g.. Phoned company and complained. They agreed to replace the tank with a new one to my specifications. And that is where I am right now. The tank will be a reef tank and I would like to move my remote 6" deep sand bed to the display tank itself. This will leave one sump for Algae growing to transport nitrate from the tank. The tank size will be 48" X 18" X 30" high. (the extra 6" on the new one to accommodate the DSB). Filtration will be this DSB, plus large protein skimmer, live rock, carbon & ozone. <All good> My question/s is/are this. Where and how would you build the holes for the outlet to the sump? Bearing in mind I am following you guys example and hope to turn the water over between 15-20 times per hour. Would you incorporate a weir? <Yes... I do strongly prefer an internal weir (internal overflow) to improve the quality of (concentrated) protein-rich skimmed water> I hope you can help me out as I do not want to fall into the same traps I have before. <Do check the archives (keyword search from our home page) for "internal overflow" and "marine plumbing". Lots of pages here to consider. Also... I have several link heavy threads with pictures/examples of the closed loop manifold and internal overflows in my "All Things Salty" forum at reefcentral.com. As far as how many/which size holes to use. My advice is actually to have a modest amount of water (say 5-10X turnover) make the loop between the sump and display. This will keep things quiet in the sump and spare turbulence/micro-bubble problems with aspiration through the return pump. Then... use the/another (drilled a few inches lower in the tank) 2" hole for a closed loop pump (this does not enter the sump loop circuit). to provide the rest of the tanks water flow needs in the display proper. Much quieter overall. :)> Keep up the great work and don't please ever give up this site! Best wishes to Bob, Scott, Marina and all of you. Cheers, Simon. <best regards, Anthony :)>

Placement of drilled holes in tank II 6/20/05 Hi Anthony, Really appreciate the reply, very helpful thanks. <You're always welcome bro> The question about the holes? No, they are not split they are one above the other and the weir encompasses them both. <Wow... a very deep overflow indeed if horizontal> But, that doesn't matter now that they are going to replace the tank. I would like to pop another question or two your way, before I give them instructions on building the new tank. It's very helpful to know that the complete 15-20 times per hour turnover does not have to pass through the sump. This does solve a few worries, thanks again for that one. <Very good... and it opens the door for more flow if you go with Acroporids, for example> What I really want to know now is, if I build the tank with two 2" holes for the outlet to the sump in the back panel at the top and two 1" holes for the return,  where and how would be the best way to surface skim the water? <This depends on the style/model of skimmer you choose. Do see the excellent skimmer threads we have in my forums (stickied at the top) at reefcentral.com (skimmer performance) and reeffrontiers.com ("skimmer 101" thread)> where would the weir go exactly? <If horizontal... as low and long as possible. About 6"/15cm deep and about as wide or a little bit thinner. And running the length of the tank as much as possible. This will thin the surface extracted water and greatly improve skimmer production. Do a search for "internal horizontal overflow" on this site and the others listed above for more info on this. Or peek in my first chapter of the Book of Coral Propagation for an illustration and detailed description> Would it be best to have an end to end weir at the top of the tank? <Yes> Also how far down from the top of the tank will be best to have the TOP of the 2" holes and the 1" ones come to think of it? <As close to the top of the tank as is sound/possible. The depth of the overflow that holds these two holes will likely be no more than 6"/15 cm at the top of the tank> Sorry to fire so many questions at you but you guys have certainly saves me from a  disaster or two in the past. (That reminds me, I owe a cold beer to all of you!) <Looking forward to it :)> Oh, one last thing. If I use powerheads (Tunze streams, thanks to Anthony and/or Scott, I would use nothing else now, they are brilliant!!) do I count these in the equation regarding total water turnover? <Yes... certainly> Cheers again. Simon. <Best regards, Anthony>

Turnover... drilled tank fitting size, pumps Hi Crew: <Greg> Anthony and Bob have been immensely helpful in the past (as have all the FAQs even if I don't have that particular problem/issue. Just fun to read!!). I have a quickie for you. I hope. I am moving soon and want to set my tank up with the sump and refugia in the basement.  Necessary info (I hope): 110 Oceanic (5' long, not the "high" version) w/ 2 - 1" overflows <Mmm, wish these openings/through-puts were larger in diameter, perhaps more numerous> 55g sump <Nice!> 2x 30g refugia <Wow, even nicer!> Do you guys have a recommendation for a pump that will accommodate this system at 15x - 20x turnover at 12-14' of total head? <Mmm, unfortunately, not through those one inch diameter fittings... Please hear me out here... You might be able to "get by" using both of these for drain/lines... pumping the water back "over the top"... and having some of the flow go through your refugiums enroute to the 55 sump... But, if it were at all possible, I would have this tank re-drilled... leaving the two current openings for returns, and adding two-two inch (or even two and a half inch) inside diameter holes for bulkheads to be used for conducting water down below...> Or should I just plan to have several powerheads? <Mmm, if necessary... but I am not a fan of such in large systems> I would prefer not to have too many powerheads as I have my tank stable at about 80 degrees F with my halides and the setup I have.  Would a pool pump be a good option or just too noisy? <Likely so... and too likely a candidate for rust troubles... Do look into the many fine lines of pumps... these are gone over on WWM> Thanks for all your help. past. present .future!!   Greg <You were, are and will be welcome. Bob Fenner> Plumbing... through-puts... 7/6/05 Hi there Great website.....learned a lot from it....... I really need some advise.......I'm setting up a new marine tank. To be exact 180 Gallons (saltwater).  My question is : what size overflow and return should I have drilled in the tank to have a good turnover of water flow. I'm not planning to have a overflow box but just risers. I was wondering if 1 1/4 inch overflow with a 3/4 return is sufficient. <I would have two each of these minimum... better to go with two 1 1/2" and 1"> I was also thinking of only drilling 2 hole with a 1 1/4 inch bulk head and having a 3/4 inch return running through it...is that a good idea... <... for what reason?> But what s really important to me is what s the best and easiest to have good results ... Thanks for your time and understanding Rick <If you're unsure, keep studying... start here: http://www.wetwebmedia.com/plumbingmarart.htm follow the linked files above, keep good notes... till you know what you want for sure. Bob Fenner> Placement of drilled holes in tank 6/22/05 Hi all, and Thanks Anthony, Have just registered on reefcentral.com and look forward to some browsing, (need more hours in each day!) <There are many great free content websites on the Net. Do consider the anecdotal nature of all though when gathering info and making a consensus.> The two holes for the drain to sump will go near the top with a weir across the back of the tank. Where would  be best to place the return holes bearing in mind I have never gone this route before, have always gone for the up & over job which personally I don't like because it's just messy. <The drilled returns are purely a cosmetic issue. Drill wherever is most convenient/attractive to you... but do know that if they are at or below the active running level of the display... they will back siphon below your overflow weir in the event of a power outage! And to use check valves to prevent this is not foolproof/safe. The best is to release water at to above the water's surface (hence the popularity of perimeter closed loop manifolds).> I am using a Deltec AP 850 skimmer which I am going to put in the sump.....(the input pump to the skimmer that is, not the whole skimmer) Oh, and I will get your book as soon as I can find it Anthony! (If you put one on eBay as a "buy it now" and let me know, I will buy it?) .... let me know?............ Cheers for now. Simon (AKA robinjoye  on eBay) <Thanks for the offer... but I'm really an anti-capitalist. I seem to make (just) enough money to feed myself despite my best efforts. Kindly, Anthony>

Overflow dilemma Hi WWM crew! <Hi Bob, Don today> I'm getting ready to set up a 30 g acrylic tank in my office.  I want to drill overflow holes at the top-back of the tank, and add an external overflow box.  I'm looking for around 300 gph through the sump, and figured that eight 3/8" holes would give me just less than one square inch of area - plenty (I thought) for 300 gph.  To test, I adjusted my garden hose to get around 300 gph by timing a 5-gal bucket to fill in 1 minute (I'm good with the math like that) .  I drilled eight 3/8" holes in a row near the top of the bucket and let it fill.  The bucket overflowed, so I drilled two more holes.  It still overflowed.  I enlarged  all 10 holes to 1/2", and then it looked like it barely kept up with the 300 gph (and that's almost 2 square inches of area).  Where is my thinking off here??  A one-inch drain pipe (.78") is supposed to be good for roughly 600 gph. <<Yep, a fallacy. RMF>> <Yes that is the current rumor, but IME it is more like 300 or less per 1" hole. I would over design and put 2-4 1" holes equally spaced across the back. If nothing else, it will leave you room for expansion if necessary and it is a lot easier to drill the holes now and cap them if you don't need them.> I'd like to get your thoughts and advice before I drill  something that won't work.  Thanks for the great job you all do !!!  Bob <Thank you and good luck with your new tank>

Bulkhead drain rate 12/14/03 Anthony, My bulkhead-drilling project resulted in 6 1.5" bulks installed across the back of my 135; I now wish I'd drilled a seventh hole, and may do so yet...the problem I encountered is that each bulkhead doesn't flow nearly what I'd hoped it might...careful flow testing with a stopwatch and a measured 6-gallon volume of the tank discloses that the maximum drain rate for a 1.5" bulkhead with the usual 90-degree threaded elbow and strainer installed is just 385gph. It seems that removing the elbow increases flow to ~485gph, but then there's no way to control water level...and of course the tank drains much lower when powering off the pump. [The bulks are draining through a vented T at the back, of course.] I thought you might find the 385gph number useful for future WWM FAQ's. Regards, JACK MARCH <yes... much appreciation for this my friend. Yet, for future readers of this message in the FAQs, your measure (albeit accurate, I trust indeed)... is only accurate for the length and run of the specific pipe/path you are using. Others with more or less plumbing, fittings, turns, etc will have differing flow rates. Nonetheless the measure is still quite helpful for perspective. Kind thanks, Anthony>

Bulkhead drain rate 11/22/03 Searching though your very informative FAQs, I get the general idea that a 1" bulkhead in the back wall of a tank can be expected to drain about 600gph; <Hmmm... to clarify: some aquarists/mfgs claim this flow through a 1" bulkhead, but truthfully it is not likely. <<Tis impossible with gravity alone. RMF>> Only occurs when overdriven (drawing a noisy siphon). Reading through the FAQs you will see that I advise folks to expect half this much> however, I recently installed one of these guys with the elbow and strainer... and was dismayed to find that his max flow was only 200gph with the elbow and strainer in place, 300gph through the open bulkhead sans elbow and strainer. <yes... agreed. And it speaks to my very common rant/peeve with so-called "reef-ready" tanks sold which really are a joke because they have too few/small holes to actually be reef-ready> (I measured the flow coming out of a 1" drain line attached to the bulkhead by simply putting a stopwatch on the time required to fill a calibrated Rubbermaid gallon container. The bulkhead attaches to a 1" T fitting to let it "breathe" as it drains. [I subsequently installed a 1.5" bulkhead, which returned a more useful 400gph through an identical elbow and strainer, running through 1.5" flex PVC pipe.]) Is this low flow a surprise to you? <nope... common. And it has been surprising aquarists for about 20 years I can recall <G>> Or has no one ever taken the trouble to actually measure the flow through these things? <ahh... there is the mfg specs. As well as the calculators on the big message boards (like RC) as well as some technical manuals on aquatic systems engineering. All to be revealed with a little digging/research by us when planning for a tank> The reason I ask is that I'm planning to drill my 135-gallon tank which is currently draining through much-hated siphon overflows, and naturally I'm trying to figure out how many and what size bulkheads to drill into the rear wall of the tank. <I would recommend enough holes (size/number) to handle 2500 GPH if this is to be a reef> The Iwaki 70RLT on the tank is probably running ~1200gph through the tank (with another 200 diverted through a UV)--so how many 1.5" bulkheads would you expect would be needed? <the above 2500 GPH to get near the recommended 20X turnover for a healthy reef aquarium> Thanking you for your time and patience, JACK MARCH <best of luck to you. Anthony Calfo>

Re: bulkhead drain rate II 11/23/03 Anthony, Thanks for your prompt and helpful response! Perhaps you would be so kind as to answer a follow-up query: <our pleasure> Although this particular tank is freshwater, I want the flexibility to convert it to either FOWLR or reef as time and opportunity may permit, so as I'm taking it offline for drilling I'd certainly want the 2500gph drain capacity you mention; <indeed... not such thing as too much flow here> but the inside back wall is just 71" long, so...the math works out to [assuming a 1.5" bulkhead will drain 425gph, which I would guess is just slightly optimistic] six 2.5" holes every 10.5" or so--which leaves just over 7" between holes. <yes... correct> Forgive my ignorance in this area, but does this much glass removed from the rear wall leave enough structural strength to contain the contents of the aquarium? <a valid question. But no worries... this is safe here. Safer still is to cluster them towards the ends (avoid the center where there is some bow/deflection to the long panes of glass)> What is a safe minimum distance between holes to prevent  half-inch glass from breaking? <its variable by tank... but as little 3" can easily be done oftentimes. This decision is to be left up to the professional who drills your tank. The other option is to simply drill fewer but even larger holes> Of course, the obvious solution would be to consider 2" bulks, but I already have the drill bits and 1.5" bulks, so I'd hate to have to re-invest yet more of my exiguous bucks in 2" hardware. <understood> On the subject of OEM "reef ready" tanks, I have a 210 & 240 Oceanic with absurd 1" bulkheads in each corner overflow; <agreed... absurd. The tanks are fine/beautiful... but the marketing/drilling/drainage is flawed in my opinion for most reef aquarists> when I bought the tanks I was such a newbie I had no idea what a huge problem this would be as I added experience and flow to the system. Really, it makes me angry--the systems as sold to me were essentially a frauds, but I was too inexperienced to know it. <alas... this is not uncommon, and most often occurs out of ignorance by your merchant, not so much as malice/fraud> By converting the two pump return lines to drain lines and using 1.5 flex PVC from the 1" bulks I've been able to bump flow to a measured 3273gph on the 240, <yes... helpful indeed. The compromise most with these systems make> but this is still far short of where I'd like it on a grossly overloaded FOWLR system. <correct> [Incidentally, it's dismaying to note how much more a vertical 1" bulkhead flows than a horizontal one!] <really... please do share these numbers/perspectives> I've always preferred WWM over RC, much less bs on your site than with the mostly BB format of RC; their flow calculator is pretty useless for addressing this issue of bulkhead drain rates, viz.,   <rather geared for experienced aquarists too> Calculators < http://reefcentral.com/calc/> ->Drain Size Calculator <http://reefcentral.com/calc/drain.php> Using the following input parameters Gallons per Hour = 2500 Drain and Overflow sizes are calculated as Recommended minimum drain pipe diameter = 2.06 inches Recommended minimum linear overflow size = 38 inches Truly I appreciate the wealth of information and sheer hard work your site represents, dunno what I'd've done without you, since I'm not much of a joiner and the LFS's aren't exactly cutting edge in terms of the tech side of the hobby; <its a labor of love on our end> one memorable comment from an LFS owner was to the effect that you certainly wouldn't want [even!] 10:1 flow in your tank--why, my gosh, that'd turn it into a whirlpool! <ughhh... what are they smoking?> Right...and weren't the '50's a wonderful time to be alive? Now lemme see where I put that Supreme AquaKing... <heehee... its with the box filters and glass wool... and coconut carbon> Regards, JACK MARCH <kindly, Anthony>

Re: bulkhead drain rate Once again, thank you for your courteous and informative response to my queries. The tank in question is a stock Oceanic 72x18x24 glass 135 with an 18" center brace, so there is no detectable bowing of the rear panel when sighting down the length of the tank. Therefore I'll assume, based on your kindly-shared expertise, that it's safe to drill six 2.5" holes evenly spaced across the back glass... <seems doable to me> and, BTW, the "professional who drills your tank" would be me, a rank amateur; but I've drilled a total of 3 holes in much thinner glass [.25"] previously, using a diamond bit and Honda coolant as a lubricant, had no trouble despite using a handheld drill, just kept the rpm's--and pressure--very low, so no detectable heat build-up. <all good... indeed a possible DIY project. Just nice to have a professional do it and insure his work> A 1" fipt x fipt vertically-mounted bulkhead [as sold by Oceanic on most of their "reef ready" big tanks] can be modified to flow at least 900gph [confirmed using an actual stopwatch and measured vol. of water to calculate flow rate] by CAREFULLY opening up the 2 male PVC adapters with a Dremel and immediately placing a 1>1.5 flush bushing inline below the bulk to bring the drain line out to 1.5", then using standard techniques [e.g., long-turn elbows or 2x45 elbows, no 90 elbows] to construct the drain line. A <very interesting... thanks you for sharing this> above the bulk is the usual Durso standpipe with again 1.5" PVC. Using 4 of these modified 1" bulks I'm easily running 3273gph in my 240. [although naturally the overflows have been lowered] But a horizontal 1" bulk will max out at a meager 200gph with elbow and strainer, or 300 running wide open--even connected to a T behind the tank to admit air and smooth the flow. I've no idea why there should be such a large difference between flow rates--vertical mount vs. horizontal--but we humble aquarists can't argue with the laws of fluid dynamics. <agreed> I really appreciate you sharing your wisdom and experience with the rest of us, Anthony! Regards, JACK MARCH   <a labor of love... wishing you the best my friend. Anthony>

Hole dia. Hello Mr.. Fenner, <Howdy> I strongly assure you that it is a great honor. I am in the process of reading your book which my spouse gave to me as a Christmas present. I have a question. I just purchased a 180 gal perfecto tank and want to run it with a 55 gal sump,. I was thinking of using 4 over flow holes evenly distributed across the back of the tank and my intention is to have a turnover rate something near 10. -What size holes should I get drilled???- I'm thinking a pump feeding 2000 gph at 4.5 feet. -does this sound good to you?- <Mmm, yes... I would make these through-puts 1 1/2" inside diameter... a few things to remark here... Do look a bit further into the actual configuration possibilities you have here... perhaps corner "towers" with the overflows drilled through the bottom, with risers as drains threaded into them... would be better> I can't find any information the applies directly to this issue. <Take a read through the many articles and FAQs folders on Marine Plumbing posted on our site www.WetWebMedia.com>   I want some good flow. Also, this will be a very lightly populated fish only with live rock. Everybody tells me not to bother with a sump and high turnover rates but I want all chances on my side and I want a couple happy fellers in my nice tank; I like the idea of higher turnover..  so what size holes do you think I should get drilled? do you think 4 is overkill? <The holes will likely be 2" diameter, and four is not too many>             Thanks so much in advance for any and all time spent on this; your work and contribution is fantastic. <Thank you for your kind, encouraging words. Bob Fenner>

Where to drill the hole 1/20/04 Hi Anthony, (or other helpful WWM crew) <Adam here today.> Please help! I have search the FAQ and other forums and cannot find a definite answer.  I am planning on drilling the back of a 75 gal non reef ready tank. I plan on  using 1" bulkheads which require 1.75" holes. My question is: where to place  the holes in relation to the top of the tank/water level? Where should the center line of the hole be? I plan on using a screw in strainer and/or a 90  elbow as I have read that will allow some adjustment. Is there a standard or good old "rule of thumb" I have read that the distance  from the top should be the diameter of the hole drilled? But does this mean from the top of the tank or from the top of the water level? Please help as I sure don't want to drill in the wrong place. No chance for a oops "do over"!  Thanks, and as always WWM is the best source of reliable information! <I have not heard a rule of thumb on this either, but I suspect that leaving one "diameter" distance from the lip of the tank has more to do with preserving the strength of the glass than anything to do with tank drainage.  I would say that that is a reasonable guide, but you may have to use an elbow to raise the water level to an acceptable level.  I would also suggest leaving several inches between holes if you are drilling more than one.  Adam>

Where to drill the hole 1/20/04 Hi Anthony, (or other helpful WWM crew) <howdy> Please help! I have search the FAQ and other forums and cannot find a definite answer. I am planning on drilling the back of a 75 gal non reef ready tank. I plan on  using 1" bulkheads which require 1.75" holes. My question is: where to place the holes in relation to the top of the tank/water level? Where should the center line of the hole be? I plan on using a screw in strainer and/or a 90 elbow as I have read that will allow some adjustment. Is there a standard or good old "rule of thumb" I have read that the distance from the top should be the diameter of the hole drilled? But does this mean  from the top of the tank or from the top of the water level? Please help as I sure don't want to drill in the wrong place. No chance for a oops "do over"! Thanks, and as always WWM is the best source of reliable information! <the distance from the surface of the water is somewhat subjective... but most folks want it as near to the surface as possible for aesthetics if no other reason. Drilled lower, however, you can extend the elbow upwards (and add pipe/tubing if needed)... however this is a possible point of leakage (into the sump at risk of overflow) in the event of a power failure. I prefer to drill high... and for a 1" bulkhead, the highest you can go is about 3" from the top of the glass on center (of the hole... thus, there will be a full 7/8" above the drilled hole). A whisker lower would be nice to play it safe. I'd suggest 4" on center from the top and use an elbow on the inside of each hole to act as a standpipe for adjusting the water level. Best regards, Anthony>

Bulkhead Sizing... Thanks for all the answers!  It was helpful! <Glad to be of service!> I have one other question though, I received my pump in the mail and attached it to my plumbing, when I found out that my overflow can not handle the pump rate (500 gph with a 1" overflow).  I then found out (albeit too late) that a 1 pipe can only handle 300 gph.  I built my overflow myself, but then I started looking at the retail ones (i.e.. CPR overflows) when I found out mine couldn't handle it.  I'm a bit confused.  These CPR overflows are rated at 600, 800, 1200 gph etc. yet they mostly all have 1 inch bulkheads.  How is that they are getting a higher flow rate with the same pipes size?  And would I be able to do something to achieve this with my current overflow? <Well,  bulkhead size is so important when configuring overflows. I cannot recall a situation where someone has regretted going with larger bulkheads (like 1.5 inches or more..). Give it a thought. Unfortunately, the best advise I could give you would be to experiment with your current overflow, and perhaps consider the addition of another bulkhead/standpipe and see what kind of results you get...Good luck! Regards, Scott F>

BH Overflow Size and Turnover...still confused !! 2/17/04 Good morning crew. sunny Scotland calling.. haha <Good morning!  Warm Pennsylvania replying...  more funny stuff!> I'm still unsure in my head if the bulkhead overflow sizes and water flow rate would be right to make this tank a successful reef tank. Here's where I'm confused I  have a 180g main tank and considering something like a 60g sump.  The 180 was drilled in the shop I bought it from with TWO, One and one quarter inch (1 1/4") holes, and I was figuring on returning the water via the Closed Manifold idea of Anthony's. <The closed manifold makes for excellent flow distribution.> Now I've read that you need somewhere between 10 - 20 times the total turnover per hour. would these 2 holes provide that kind of throughput,  <Are the holes 1.25" (likely only to accommodate 3/4" bulkheads), or do the holes accommodate 1.25" bulkhead fittings?  As a drain, 1.25" bulkheads will probably accommodate in the nationhood of 5-600 gph each, leaving you quite short of your target flow rate.> and if so what rate/kind of pump would you recommend (I'd prefer an external one if possible). <Iwaki is widely considered to be the "gold standard" by which all centrifugal pumps are judged, but GRI and Little Giant also make excellent pumps.> As a side thought, although the holes are only 1 4", as the bulkhead fitting comes out of the tank, would it help any to increase the diameter of the pipe here to speed up the water rate ?? <For returns, lager diameter pipe is helpful to increase flow, but this effect is very much diminished for drains.  If you find that you are not satisfied with the amount of flow that your drains can handle, you may have to supplement with other types of circulation.> Many thanks Raymie (Scotland) <Best Regards!  Adam>

- Turnover - Can I get sufficient flow through the overflow on a 125 reef ready all glass tank using a Blueline 40 HD-X pump. <I think so... if it has two overflows, then it should be no problem.> Will I need to run all 4 bulkheads for drains or will the 2 one inch be enough. <The two should be sufficient.> Any suggestions I am trying to convert from J tube overflows to internal type. <I take it then that this is a new tank.> Tank has been set up 9 years and is stocked with SPS LPS and soft corals. <No worries. Cheers, J -- >

Tank Drilling Hello, Just  a quick question. Should I have my glass 120 gallon (tall) tank drilled in the bottom or out the back?   Thanks! Todd <Hey Todd, I have seen both ways work, but personally I would drill the back of the tank (assuming that it is not tempered glass).  I am a firm believer in if something can go wrong it will.  Myself, my floor, and my landlord would much rather have a leak on upper back of the tank than the bottom.  I have never seen 120 gallons spilled on the floor and really do not want to.  Best Regards, Gage>

Re: Tank drilling Sorry to persist.... <Don't know what's going on with Gage's email but I'll give it a go> But I have just a few more questions.  I am trying to find someone who will drill the tank.  Most everyone does not want to attempt it.  The only glass company that is willing to try it, sounds a bit flaky. <If this is a glass tank... much easier to drill before assembly...> If it were your tank (I know.... you would have bought it drilled), and you had to have it drilled..... where would you have the holes drilled (I mean can you be very specific, as in inches from top and sides), and how many holes, and what size?  Also where would you purchase the bulkheads? <How big a tank? If it's a small one (less than more than a couple of feet in length/width, a couple of inches from the edge and top (you can manipulate the level of water inside the system with plumbing outside) to give you some "edge" for structural strength> Would you ever consider using a HOB overflow?  If you had to use a HOB overflow, would you use a double intake type? <I would, have... even built, manufactured these years past... and I like the "waterfall" varieties better than the double intake designs, but greatly favor the doubles over single tube types> I very very much appreciate your input. Thanks, Todd <You're welcome. Bob Fenner>

Re: Tank drilling Thank you for the super fast response. <Now it's the 18th?! Yikes> Where would you drill the holes at in the back?  And how many?   <Ahh, I see below from previous correspondence this is a 120 gallon system (likely six feet long). I would drill at least two, maybe three holes... if two, 2" inside diameter, and if three, 1 1/2" inside diameter... two at either corner set with two inches of glass at top and the side and the third at the same level in the tank mid-back> Can I just drill several return holes and avoid having to use powerheads inside the tank? <Yes> Do I still need to use an internal overflow? Or can I just put cages over the outlet holes? <Can use either one, I prefer the latter> And how many outlet holes should I have drilled? <IMO two> How can I determine if the tank is tempered?  If it is tempered, am out of luck having it drilled? <The folks doing the drilling will be able to tell you. More likely than not the glass is not tempered though.> I appreciate all of your input. Thanks again! <You're welcome again. Bob Fenner>

Re: Tank drilling Thank you very much for the replies. <Welcome> If I drill (3) holes 1 1/2" which should I use for the returns? <One inch ID should be fine> Or should I drill more for returns?  I suppose I could just drill (3) holes and use the center for the output and the two end holes for the returns? <I would use two more holes for the return... about the same level a few inches from the overflow holes (you can fit manifolds, diverters inside the tank... threaded on to the bulkheads/throughputs>   I guess I could then find some ball jets that could attach to the bulkheads to divert the returns any angle I wish? <Ahh, yes> I also imagine that I would need a stout return pump to push lots of water? What GPH size pump would you recommend?  I was looking at the Velocity T4, but perhaps that is not enough flow for the returns to have good water flow? <Depends on a few factors... will you have a sump style filter arrangement... at what "head" (difference in water level)? Or will the pump have to "pull" or push through a mechanical filter membrane of some sort? Much to consider> The above should cover it.  I very much appreciate your thoughts. Thank you again, <A pleasure to share with you. Bob Fenner>

Re: Tank drilling Hello, Yes this would be for a sump style filter.  The head would be approx. 3 - 4 ft. Just to reiterate.  I should drill (3) 1 - 1/2" holes approx. 2" from top and sides.  One being in the center. Then also drill (2) more additional holes for returns.  These should be drilled about the same level and a few inches from the overflow/outputs. It sounds like I would then bring the three overflows down into one or two lines going into the sump.  From the sump/return pump go to the (2) return holes on the back of the tank.  These (2) return holes can then be used to divert the water at whatever angle is best suited via eyeball diverters. Thus eliminating the need for powerheads. <Yes> However, the pump will need to push enough return to make this useful.  At the same time not drain the sump too quickly.  Any suggestions on keeping this balanced? <Mmm, yes... an oversized pump with a throttling mechanism... likely a ball or gate valve... the water going into your tank will surely overflow back into your sump/refugium... the most important item (other than making the sump as large in volume as possible) is to initially fill all, turn the pump on and mark the level in the sump... and NOT fill the sump up any further than this...> Would hate to drain the sump or overfill it.  Perhaps a few ball valves installed inline to fine tune/adjust the flow? Thanks! <That's the ticket! Bob Fenner>

- Don't Rush - Attached is a picture of my 75 G tank I'm building. I should have sent this email prior to drilling the holes, but when you have power tools in your hands its often shoot first and ask questions later. <Whatever happened to measure twice, cut once?> I hope I didn't just shoot myself in the foot by drilling 18 9/16" holes in the top back of the tank for overflow. . . Did I compromise the structural integrity of the tank? <You may have... just looking quickly at that picture had me concerned... not sure there's much there at the top edge to actually hold the top to the back piece in that area.> I've read quite a bit about your collective frustrations with 'reef ready' tanks not having enough overflow capacity for the needed water volume for a happy reef, and my own experience with my first 37G mini reef indicates to me that water flow is where it's at (I'm turning over 27x in my 37G and things are going reasonably well considering my general ineptitude. I haven't killed anything yet ;-). So if my return pump is doing 1200gph, are my 18 9/16" holes enough for the overflow? <I really don't know, but I don't think so...><<No way. RMF>> The plan is to glue on an acrylic overflow box to catch the overflow water from my holes, punching a 1" bulkhead in the bottom of that to drain to the sump. <Scary plan.... a very good chance the box you glue on will one day fall off without anything to actually support it but the glued seam.> While I have you, you can see my return manifold in the picture as well. The plan is for the Iwaki MD40RXLT (Awwwww yea!) to pump it's 1200 through the manifold. <Chances are good you'll be below 1200 GPH after you make all the turns a manifold implies.> I'm also thinking of punching a set of bulkheads through the back of the tank and running a mag7 in a closed loop to keep the back of the live rock clear. That would give me a total of 1900 GPH flow. I know that in general it's nearly impossible to give too much water flow, but am I wasting my money going w/ the additional mag7? <No.> thanks for your help. Your team is awesome! Kevin
<Cheers, J -- >

Where Does The Hole Go?   Hi, I have a 30 gal. reef and want to add a refugium. I have an old 10 gal. sitting next to the 30 gal. it is full of 7 or 8 macro's and the bottom of the 10 gal. is even with the top of the 30 gal. I want to run a canister filter from the 30 gal. to the 10 gal., and drill a 1 inch bulkhead in the side of the 10 gal., and let the water return with no pump via gravity. I am not sure at what height to place the hole? I know near the top would give more water in that tank , but I am concerned about the amount of critters that would make it to the main tank with the return near the top without having a power-head in there stirring everything up?  Thomas Giddens <Unfortunately, Thomas- that's one of those things that you're gonna have to experiment with. I'd advise placing the hole towards the top, myself. Regards, Scott F>

Drilling Question Hello again, WWM crew ! This is Luis Santos from Portugal, do you read me over...? <Loud and clear, over.> I have this 65gl already established marine tank (8 mm glass). Since I'm waiting for a new custom built steel stand (not only for the weight, but also to get space for a future sump), I'm beginning to think about getting the tank drilled. But what would be, in your opinion, the ideal drilling diameter, and also where to drill, side or bottom? <I would drill the tank to fit whatever bulkheads are available. If you can get 1" I.D. bulkhead fittings (the most common), I would get three to four holes drilled in the back spaced out and about 4" from the top of the tank to the center of the holes.> Also I would like your opinion on return pump size and... <A pump capable to 650 gph at whatever head pressure you have as a minimum.> Yes I know sump size the bigger the better, right? <Yes> Thank you again! Luis Santos <You are welcome. -Steven Pro>

Overflow sizing Hi Bob! First let me say that your book is excellent, I just finished reading it and your site is packed with great info. <Thank you for your kind words> I am setting up a 100g acrylic tank and I am building a 30g sump for it. I will build an overflow box on one side of the tank with a standpipe in it. I am using a Turboflotor skimmer with an Eheim 1060 pump feeding it and an Eheim 1060 pump for return. <Very nice gear> The question that I have is on sizing the overflow. I am planning on making the standpipe 1 1/4 in the box and then from the box to the sump 1". I will then use a "T" with valves controlling the flow to the skimmer and the sump. The return will be 3/4" on the opposite side, and all of it will be with flexible pvc. Do you think this setup is ok and do you have any suggestions. <Mmm, just to be on the "safer" side... I'd increase the diameter of the lines stated to 1 1/2 and 1 1/4" respectively... Bob Fenner> thanks in advance Jim

Overflow Tube Size Hi guys/gals- <<And hello to you...>> I am looking for your guidance once again. I am setting up a 125 AGA salt tank & 2 corner overflows with fish and live rock. An upgrade from a 5yr old 55gal set up. <<Interesting, just moved my 54 into a 180... have fun!>> I have been told that the 1" bulkheads will move about 600gph each. If I stepped the 1" pipe up to a 1 1/4" right after it is connected to the overflow at the bottom of the tank ,will this improve the flow rate at all? <<Not above and beyond what you can get through a 1" bulkhead, but I think that is actually higher than 600gph - I think this specification may be that of the overflow.>> I would still have the 1" bulkheads but I thought the larger diameter would move more volume from that point on. <<The bulkhead is the limiting factor, even though it's not really limiting you.>> I have a 2 magdrive12 pumps and am not sure if I need both or not. If I used both I think would need more overflow than the 1" bulkheads can provide. correct? <<Well, I think this pump is rated at something like 900-ish at a 4' head, and even this would be more than 600-gph per overflow. I'd try it when you do your leak test, and just plumb in valves on both pumps so you can dial them back a notch. More flow is always better if you can do it.>>  I am keeping Tangs (Naso, Sailfin, regal blue and yellow) ,live rock and 2 Condy anemone, lots of snails/hermits. Plus an arrow crab. I have a 30 gal refugium and a 20 gal sump. Do you think that my tank would benefit from the increased flow from two mag12 pumps? <<Oh yes.>> Could I use both pumps and close down the shut-off valve a little bit on both without damaging the pumps? <<Any restriction/valve placed on a pump should be done after the pump... if there is a valve in front of the pump, use this only to shut off the line and remove the pump for service.>> I am not sure if this idea is nuts or not...... <<nuts... you mean like true-unions? These are excellent - use them everywhere you hard-plumb. Or do you mean the nuts on the bulkheads? If these make you nervous, smear some aquarium silicone on the gasket and put it together. It will be fine.>> Could I tap off of a overflow line with a T and run some water into the refugium and have the overflow from the refugium tap back into the same overflow line farther down line? No pumps involved. Both T's would be before the sump. <<You could - might be best to try and arrange the refugium above the sump so that it could overflow into the sump. Is this what you were thinking?>> The reason I ask is that I am hoping I can keep the refugium under the main tank on display but sump, pump, skimmer, etc.. would be on the other side of the wall in the room next door. <<Oh... sure. If you are taking the time to do a built-in with separate room, for certain.>> Thanks and have a good weekend!!! Den <<You too. Cheers, J -- >>

Overflow drain size vs. flow rates I'm finally doing it, converting my FO tank into an SPS tank. After exhaustive research, I've pretty much settled on my final tank parameters and equipment list, except for one thing: flow rates. From reading through the correspondence on your website and checking various other sources, I've been convinced that I need more than 10X GPH flow rate for a successful SPS tank.  <agreed that VERY dynamic water flow is necessary.... please save your money on silly wave timers/oscillators. Simple and strategic random turbulent flow from converging outlets grows coral VERY well> Since I have a 180, this translates into at least 2000 GPH, which I would like to achieve without the use of powerheads.  <agreed on both counts> The tank only has a single 1" i.d. bulkhead in the corner overflow, however.  <wow!!! that is staggering and a fraction of what you need> Am I correct in assuming that this single overflow is not going to be sufficient to handle 2000+ GPH?  <more like 300 GPH!!! without a siphon or sucking noise> I can't seem to find a chart or any other hard data on overflow size vs. flow rates. Do you know where I can find this information?  <yep... Rainbow lifeguard and any other manufacturer of bulkheads> What are the maximum gravity fed flow rates through a 1", 1.5", 2", dual 1", etc. bulkheads? What do you recommend?  <no more than 300 GPH per 1" drain. I have 4 holes (!!!) in a 50 gallon getting 1100 GPH and that is barely working> I appreciate any help/advice you can give. Thank you, Will FYI - my tank/equipment list so far: 180g acrylic (already had it) 3 - 250w MH 6500K 2 - 140w 60" Super Actinic AquaC EV-180 skimmer <excellent lights and skimmer> Korallin reactor 1/3hp chiller DIY sump return pump(s) tba <I recommend Iwakis> <best regards, Anthony>

He Has BIG Bulkheads! Wow!!  I just got my bulkheads in, I had ordered 4, 2" bulkheads (2 for the tank to drain water to the sump and 2 for the sump to receive water from the tank) and 2, 1.5" bulkheads, which were to be used for my 1" pumps, so the pumps would always have enough water feeding them, I read this was a good idea. <I agree, especially if you're like most reef enthusiasts, and will one day up the circulation in your tank with a larger pump> So, I'm looking at these 2" bulkheads, and they are HUGE!  Do I really need to use 2, 2" to drain the tank to the sump?   I guess you can't have to much overflow, but wow, I didn't know how big these bulkheads would be! <Yep! Those are large bulkheads! However, I think it's not a bad plan. Was it Billy Idol or Donald Trump (what a contrast) who said in the 1980's that "...Too much is never enough?"> The tank is a 125Gal, and will have about 40gal worth of sump/refugium, and plan to use a MD55RLT as a return pump, should I really use both 2" bulkheads for overflows?  or maybe just 1?  wow these are big lol... <Maybe install both, cap one, and have the other available for future expansion...?? Mark <Good luck, Mark! You'll have a lot of options in the future with this setup! Regards,  Scott F>

Holy Bulkheads Batman! Wow!!  I just got my bulkheads in, I had ordered 4, 2" bulkheads (2 for the tank to drain water to the sump and 2 for the sump to receive water from the tank) and 2, 1.5" bulkheads, which were to be used for my 1" pumps, so the pumps would always have enough water feeding them, I read this was a good idea.   So, I'm looking at these 2" bulkheads, and they are HUGE!  Do I really need to use 2, 2" to drain the tank to the sump?   I guess you can't have to much overflow, but wow, I didn't know how big these bulkheads would be!   The tank is a 125Gal, and will have about 40gal worth of sump/refugium, and plan to use a MD55RLT as a return pump, should I really use both 2" bulkheads for overflows?  or maybe just 1?  wow these are big lol... <Do use both, two... better too many, too large than the opposite... for redundancies benefits. Imagine one of the overflows blocked... Bob Fenner> Mark

He's Got Big Bulkheads (Pt. 2) Well, I think if I build and hide them behind an internal overflow box it may not be so bad...2" is hard to plumb...the parts are hard to find and expensive (compared to 1 1/2").  The biggest eyesore is the elbow and intake screen in the tank, to get this to work with this threaded bulkhead, it will stick out like 5 inches and look awful in the tank! <Yep- not the most pleasing thing to the eyes...> If I were to pick up some scrap acrylic (I assume any kind will do for this since there's not much pressure) Could I drill the hole in the back wall of the tank, and build an overflow box that didn't go all the way down to the bottom? Just to skim the top and cover up the bulkheads? <Yes! This is exactly the idea presented by Anthony Calfo in his "Book of Coral Propagation". It's a great idea..> It looks easy enough to build, is there any special size or gap the grates need to be in the overflow to work with this size bulkhead?   <Nope. My only recommendation would be to have more than you think you need- you can always cover them...> Would the below 'picture' work?  assume the "O" is my 2" bulkhead in the back wall of the tank. |  | |  | 0__| | | |

Drilling Aquariums for Overflows Hi Anthony... Hope you are well! <cheers, Jenny! With hope you are too> I sent an e-mail to you at your home address regarding further info I needed for my new tank. As I have not heard from you I guess you didn't get it or you have been to busy to check your mail there. Should I not have sent it there? <my sincere apologies dear... I did receive it but have been buried in communications as of late. It has been a struggle just to keep[ up with our WWM mail. My apologies again> I thought I would because it is the same subject I have been asking about and so thought you wouldn't want it on WWM to bore your readers with. <not at all... we prefer to share all with the WWM readers for our mutual benefit and information exchange> In short the LFS I'm getting the tank from say that the tank manufacturers won't do the spec he has sent them (which sounds like 6 holes of 53mm) without a signed waiver in case the tank fractures. <not a surprise...they are all conservative... and look for ways to skim extra profits on "custom" orders.> They say there must be a second 10mm back panel of glass siliconed to the first and also a  6mm safety panel in the overflow shelf you recommended (don't understand or see the need for the overflow shelf bit) <I totally agree... the extra back panel is sensible... the internal piece is a sham> This means 12 holes in all at a cost of approx. 22 USD per hole i.e. 264 USD just for holes! <that's ridiculous... they should have just suggested 2 large holes instead and none of this would be needed. The number of holes is unimportant when an internal overflow box is used... that's what stretches the skimmed water and concentrates it. I did not/cannot recommend a specific hole size as I am not familiar with the available metric plastics/bulkheads in the UK. Still... you get the point from the diagram: any number of holes large or small to get the flow you need. Mfg specs for bulkheads will confirm flow ratings> Can you just tell me a safe number/size of holes to drill to give me the flow rate of 2000 gph without the need for all this reinforcement they are saying is needed (6 holes sounds a lot to me anyway). <six small holes (1"/25 mm) would not be a lot for this tank. But 2 or 3 larger holes (say... 40-60mm) would likely work as well> If you can tell me this then I will tell them to do it and sign whatever they want just to get my tank! <If the back reinforcing panel is not expensive, it is sensible and worthwhile. Too bad the extra hole drilling is priced so ridiculously. It sounds to me like this manufacturer does not have much experience with custom work. For this we are blessed here in the US, I suppose> Anyway thanks a million for all your help and I promise not to bother you  with this one again. (notice I only said this one) Thanks again - Jenny <no bother at all, my dear... best regards! Anthony>

Overflow- undersized as usual Quick question I keep forgetting to ask.  I have 2 1.5" bulkheads drilled into the back corners of my 75gallon tank. I am wanting to surface skim by putting 90 degree elbow attached to the bulkhead in the tank. (also help in the event of power failure/siphon) But... I can not get rid of the water swirling/sucking into the elbow.  Looks like a tornado sucking into the 90 elbow and it sounds terrible.  Any suggestion on what I can try? Thanks Bryan <This is a common problem bud... the overflows are simply too small in size or number. A common problem. What is happening is that your "oversized pump" (really not too big... just too much for the lack of holes/size) is pumping faster than they can gravity overflow and a siphon is being created (the sucking noise). Put a gate valve on the outflow of the pump and slowly restrict its volume returned topside until the noise stops. How ironic... you'll have to restrict the pump and then add power heads in the main tank to compensate for the lack of water flow (adding heat, electricity, eyesore, etc). Bummer dude... but a common problem from bad advice and poor overflow design by the manufacturers of tanks. Best regards, Anthony>

Overflow capacity Hi, I was just wondering if you happen to know what the max rate (gph) a prefilter can handle with a 1" tube at bottom of tank, as far as how many gph pump could I use w/out overloading. I was thinking of a little giant pushing 1000 @ 3'. <A 1" overflow pipe will not handle 1000gph, better surf over to one of our sponsors and look at what flow 1" overflow boxes will accommodate. Foster and Smith carry CPR overflows with 1" pipe that have gph flow rating.> What external pump in your opinion is the most quite for an external pump. Thank you for your help ! <Iwakis (Japanese, not American) and Custom Sea Life are popular quiet external pumps. You will need the overflow capacity to handle these!  Craig.>

Overflows in Glass Tank Hi to all and thanks for the answer Anthony, I have the 55 gal corner bow tank Aqua C Remora, and magnum 350 canister Here is a picture so we are on the same page. I did all the things new fish keepers do and bought everything without any research.  That was a year and a half ago.  I built the Cabinet as well as a matching one in another corner with a TV on it.  Maybe some day that will get a matching tank on it after I throw a brick through the TV haha.   We are currently going to add a DSB (in the trashcan to the left) and live rock (in another tank).  I have discussed an upstream refugium  and the wife doesn't like the idea of another tank on the wall.  She dislikes it enough that she has given up on having the Green Mandarin.   I want to put in a sump in the cabinet below and a 20 gal high will fit nicely.  That way I can hang the Remora Pro down there as well as the heaters.  Are there any other reasons that a sump is a benefit (to convince the wife hehe)? <Hiding all of the heaters, pumps, powerheads, etc in the sump makes the tank look cleaner and less cluttered. The added water volume stabilizes the system and allows you to make water changes, supplement etc. in the sump. Much easier!> If I do put a sump it seems like I would need to drill the tank.  The bottom is tempered glass so that is out, but I could drill the back.  Could you please explain how to determine the height of the hole so the 20 gal does not overflow when the power goes off. <The hole should be <sic> several <<a few. RMF>> inches below the desired water level, a 90 degree ell threaded/glued into the bulkhead turned UP to the surface. Insert pipe into ell as long as needed to place top of pipe at the desired water level, minus about 1/2 for water to flow over the top of the pipe. IOW, the water is pumped into the main from the sump, UP to the top of the overflow pipe, and then when it overflows the pipe it drains into sump. If pump goes off, the water cannot be pumped over the top of the pipe and it all stops.  Make sure you put siphon breaks in your *return line* so they don't siphon in a power outage as well. Ask your local glass supplier about drilling glass.>      Also what size and how many would you put in this tank?  There are so many different schemes for doing this that my head is killing me. (could be the Guinness though).  You have really helped us out in the last six months since finding your site so I really wanted your advice.  This seems like the time to do any modifications since is nothing in the tank. Thanks for your help  Bryan and Dana Flanigan PS sorry this is so long.  We are stuck at home in this blizzard with nothing to do except yell at the kids and dream of ways to spend money on fish. <Depending on what you want to keep, 10 to 20 times turnover is needed. So, from 550 to 1100 total turnover. The WWM sponsors sell overflow boxes that are flow rated with various pipe sizes, head over to one of the sponsor sites and size your overflow bulkhead(s) according to these flow rates/pipe sizes. Oversize by a safe factor. IE: I would likely go with a 1/1/2" overflow in case I want a closed loop circulation system in the future or if increased flow rate is desired with growth, change of plans, etc. I suggest over-sizing plumbing by one or two sizes to allow for adjustability/growth.  Best of luck!  Craig> 

Bulkhead placement and noise 2/16/03 Hi guys real quick one.  I have 2, 1.5" bulkheads drilled in the top back of my 75 gallon tank.  I decided to add a glass overflow (like Anthony describes in his book) about 1" wide along the entire back of my tank.  This has been siliconed and really looks good.  So I filled my tank up (again) w/ tap water to test everything out.  Well....I don't think the overflow works quit like I hoped.  Don't get me wrong, it pulls a sheet a water directly from the surface, and works great w/ a simulated power outage, but the problem is the water going into the bulkheads. I don't know how I thought it would work, but here is my problem.  As the surface water runs over the overflow there is about a 1-2" space at the top of overflow where there is no water and the bulkheads are sucking the water in, in fact the very top of the bulkhead is not in/under the water so I am getting a sucking noise.   <if I understand correctly... the top of the bulkheads are actually slightly higher than the top of the overflow? If that's the case... no worries... drain the tank slightly and silicone an extender piece of glass to the overflow> I have been told b/f that this could be from a pump pushing more than the bulkheads can handle <almost certainly the case... not a problem even with your high placement of the bulkheads... that has nothing to do with creating a siphon> (pump is CSL velocity T4) but I have tried turning down the return w/ a gate valve and it doesn't help (turned the flow almost off even). <Doh! you fit the bill, bubs. A common problem where aquarists don't drill enough holes or put too large of a pump on. The ratings for bulkheads are a joke. What they can run under pressure (or creating a noisy siphon like you hear) and what will run safely and quietly (half filled pipes) are two very different things. The common 1" bulkhead is rated at 500-600 GPH per hole. But at that rate... it is noisy as all get out! 1" bulkheads really should only handle about 300 PGH each to be safe and quiet. Thus... to run a 1200GPH pump, you need 4 bulkheads! With your 1.5 inch holes... I'd guess you could only run about 1000PGH trough them quietly. If your pump is pushing more than that... you have your answer IMO> I always read that the best way to have tank is drilled for bulkheads, instead of built in overflows w/ bottom drains to pump.   <not much difference in flow here... just noise (the floor holes/towers are much louder)> But it seems almost everyone has these and builds a Durso standpipe and everything is quiet.   <this is just an engineering issue, my friend. Holes drilled on the back wall and sized correctly for the pump do not require a modification like the Durso. You just don't have large enough holes/bulkheads> I don't have this type of set up, my tank is drilled on the back w/ bulkheads and I can't hardly find anything about how to get flow from the tank/bulkhead to the sump and the quietest way to do it ( Nightly I read over WWM, reef aquarium guide, reef central and reefs.org) Please Help.  I'm ready to get the tank going again but have been dealing w/ this issue for about a month or so.  I might even rip the overflow off and try 90 degree elbows again and try to rig something else up.   <will not solve the problem bud... cut that pump flow back to 1000GPH and you hear it quiet down> I even tried the elbows b/f, but again had a terrible sucking noise, and yes tried turning the pump down, still did not help.  Any suggestions, I'm just feed up.  Thanks Bryan   <no worries bud... a miscalculation. Easily corrected. Best regards, Anthony>

Re: Flow Rate Thanks in advance for the help! What rate of flow could I expect from a 2" pipe stemming from an overflow with two 45 degree turns? I have six such pipes on my tank and I want to match up the two return pumps correctly. Thanks. signed--- "Waiting to Buy Iwakis" <2" pipe can drain approx. 2000gph passively,  <<You're high! Or dreaming... no way. RMF>> but do be conservative in your estimates. I have two vats with 2" overflows, one drains 1800 gph easily, and the other drains 2000-2400 gph, but with an elevated water level as it is almost at capacity. Hope this helps!  Craig>

Overflow volume and noise Hello, Getting ready to drill a 120 gal. tank and have a concern about the noise from the overflows.  I am hoping to turn over the volume of the tank at 20-22 times per hour. I have read that a 1.5" overflow (PVC) can drain water from the display tank  into the sump at a rate of 600 GPH (I  plan to "T" the 1.5" PVC on the outside of the bulkhead so air can escape as the water runs through the overflow into the sump). <Easily 600gph. <<Uhh, not so. RMF>> Go to one of our sponsors like Foster and Smith, Quality, etc, and look at the flow rate of add-on overflow boxes with 1.5" pipe. If you are concerned with noise, under-using the overflow/plumbing size and using Durso style vents (like you intend) is a good plan. The water actually doesn't make any noise....it's the AIR being *sucked* into the drain that makes the noise. If it flows rather gently with enough room for a reasonable amount of air while draining it will be quieter.> I think I read somewhere that the 1.5" overflow can move 600 GPH,  BUT will create a lot of noise as it moves that amount of water.   <Probably not. A 1" pipe is rated for 600gph, <<As a gravity drain? Not even in a perfect universe. RMF>> so 1.5 is considerably more. Still, you will do well to use oversized overflows for noise reasons.> The suggestion was to plan for the 1.5 overflow to move only 300 GPH (1/2 it's capacity) and it will move the water much more quietly. <Please do check out the rating of the overflow boxes with 1.5 " pipe.> Is this true? <The theory is true, the sizes/flow rate need to be changed to protect the innocent.> If so I will refigure my plumbing and drill extra hole(s) and only expect the overflows to carry 300 GPH- but quietly. I continue to use your wonderful site daily! Thanks <Bigger is better, but 300 gph through a 1.5" pipe is probably a little overkill. They will do 600 gph without much problem. Check out the overflow plumbing, it will help!  Craig>

Overflow sizes and placement How many inches of hole equals g/hr? Best place for overflow holes? <I would use the calculator at Reef Central or look at the pipe sizes for aftermarket overflow boxes for a guide. Best to shoot for a higher flow and control with valve on the return pump. 10-20 times tank volume total turnover. The best placement depends on the size, layout of the tank, inhabitants (make special considerations for anemones, small fish, soft bodied inhabitants, etc.). Best to check out marine set-ups at WetWebMedia.com or perhaps a good basic book, it will come in handy.  See the books forum at WetWebFotos.com for revues by hobbyists.  Craig -A few questions...- Hello, First, Thank you for the extremely valuable information you provide freely on WWM.  I am just getting started with this hobby (probable obsession it seems).  I have read nearly all the FAQ pages on your site over the past 2 weeks, and have posted my proposed setup on the forum for some valuable insight from the veterans of this hobby.  I am attempting to plan my system carefully before even starting to assemble it.  I am sure I will still find many questions along the way, but I hope to harm the least amount of SeaLife in my care in the process. <Sounds like you have the right attitude!> After all this reading, I still have a question about plumbing my overflows, a question about the overall flow, and a question regarding lighting. I am setting up a 125gal 48x24x24" tank, and am in the process of arranging to have it built. <That's what I have! The standard AGA or Oceanic 48-24-24's are 120's, when I think 125 I think of a 6' tank> I plan on ultimately having a reef setup...after a long period of fish and live rock only.  Even though this is in the future, I am planning for this from the outset. <Good idea> The specifics of my proposed system are in the forums, and I will not waste your time with them here. I plan on having a 25 gallon sump and a 20 gallon refugium set up below the main tank in the stand (already have measured everything out for this to fit).  I plan on having the sump baffled with the final chamber receiving overflow from the refugium and pumping this chamber back to main tank with two Eheim 1262 pumps in parallel for the redundancy factor.   Now, for my questions: I have never seen a direct answer to this question...will two 2" inside diameter overflows (one in each rear corner) provide adequate return flow for the two Eheim pumps listed (898 GPH at 0' head, I will have approximately 4.5' head so I am guessing about 1200 GPH between the two pumps) <Since we generally use 2 1" drains on pre-drilled tanks, a pair of  2" drains should be more than enough.> Next, will this be adequate flow for some of the hardier coral species?  I plan on the pumps returning to opposite sides of the tank and going through a SCWD on each side for 4 total nozzles (one in each corner). <Nice, you'll like the "squids". The flow needed will depend on the coral that you have in the tank. Increasing flow means simply buying a powerhead or two or setting up some sort of closed loop. Not a biggie, nothing to worry about.> Finally, I have read and read on this site as well as done searches on google and everyone seems to gloss over this basic Newbie question.  I know I need timers for my lights, but even looking in the online merchants, I can only find IceCap timers specifically for aquarium lights.  I plan on using PC lighting (tank is 24" deep because of this, I didn't want to go to MH lights). <24" is pretty deep for PC's> I cannot find timers specifically for these PC lights, and have even looked on the manufacturers sites...all that is ever mentioned is "timers" does this mean to use standard home lighting timers like you can purchase from a hardware store? <Yep, you can find analog or digital timers at pretty much any store. You don't treat the PC's any different than you would a household lamp.> Sorry for the long post, but I really did try to find  discreet answers to these questions before mailing you.  I just don't want to end up with a system that is poorly planned from the beginning and limits me in the future. <Sounds like your heading in the right direction, I wish you luck! - Kevin> Thank you in advance for your time, Kevin (SaltwaterNewbie on the forums)

Size Does Matter! (Bulkheads and Standpipes) Hello again, <Hi there! Scott F. back with you tonight> I appreciate your help and insight on setting up my new 180g tank, but I have a few more questions about the overflow.  I finally got a reply from Oceanic about the size of their overflows and their philosophy about those sizes.  Apparently their theory is that 7-10x turn-over in an hour is sufficient.  For that turn-over rate the drain is a 1-inch bulkhead and the return is a 3/4-inch bulkhead.  Now to go along with what you recommended and I agree, a Dolphin pump (3200+ gph), will the above size drain and returns be sufficient or should I have them drilled bigger by Oceanic?  If so what size? <If it were me, I'd think about 2 inch bulkheads...> I don't want to have problems with my system because of limiting bulkheads. Secondly I was thinking about adding Durso Standpipes.  If you suggest 1 1/2-inch drains what size standpipe?  The same with 2-inch drains?  I have read that for 1-inch drains you should use 1 1/4-inch standpipes. <I believe that you're correct, but the exact proportions seem to have escaped me...You can visit Richard Durso's website (do an internet search to get the URL) for his input regarding sizing and configuring overflows...> Lastly, I was thinking that I might need to put a single union ball valve where my pump will connect to the bulkhead at the sump and regular ball union valves at the bottom of each bulkhead of the aquarium drain for when I do tank or pump maintenance.  Does that sound advisable. <I do that with my pumps, and I think it makes perfect sense. In fact, you'll really appreciate it when it comes time to replace the pumps...> Thanks for your help. Daniel <Glad to be of service! Regards, Scott F>

Internal Overflow Sizing... I have asked this question on multiple forums and haven't got a satisfactory answer.  I just picked up a used  180 gal to upgrade my reef tank. It has two- 2" holes already drilled in the upper back glass, approximately 4" apart. I would like to build an internal overflow with "fence" or "teeth" type construction to prevent fish, et al. from taking the journey down into the sump. Ideally, I'd like to have roughly 3000gph as a turnover rate. Can you point me to a formula or make a recommendation in regards to dimensions for an internal overflow which can handle this rate? (including the width of the spaces and teeth)? Looking forward to hearing your solution for this. Jeff. <Well, Jeff, the 2" diameter standpipes in the tank can handle a decent amount of flow (at least 1500gph. However, for a lot of ideas on the proper construction, sizing, and configuration of overflows, you can't beat the resources found on the DIY site, ozreef.org. Check out this link: http://www.ozreef.org/diy/index.html#OVERFLOW Hope this helps! Have fun with this project! Regards, Scott F>

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