PVC Size/rate of flow 6/16/08
Hey All! I hope your Saturday is going as well as mine!
<Hello, it is/did!>
I am sorry to bother you with this, but I cannot seem to find the answer myself.
<No problem.>
I am in the plumbing stages of my 150 setup – it will be plumbed through the wall into a 120 refugium and a 55 sump. Can I tee the 2 x 2” drains from the 150 into a 3” to go through the wall or should I use 4” PVC instead?
<3” will yield enough flow to handle dual 2” drains.>
The answer will then allow me to determine how far from the wall the stand needs to be. I would hate to go with the 3” only to find it to be too small, and although it may be easier to just run both 2” drains through, I’m thinking that on pipe through will look much cleaner.
<Your choice, dual 2” lines may very well be easier to handle and setup.>
Thanks in advance for your help. I have been an avid reader of the FAQ’s for several years – the help all of you have provided me (and countless others) is so very much appreciated!!!!
<Thank you very much for the kind words. You’re welcome, always a pleasure to help, Scott V.>

Drains, Returns and Closed Loops, OH MY! 6/1/08
Hey Guys!
<Brian>
So here's where I am at and need some plumbing help. I have a 120g (48.5x24.5x24) AGA with center overflow that has a 1.5" drain. The tank is also drilled with 4 1" bulkheads along the back. I originally was going to use just the 1.5" to drain to the 40g breeder sump, and 2 of the back holes for returns with the other 2 for closed loop intakes, but after much reading on your site I think it might be best to change that train of thought.
So here is where I am at, and would love to hear your thoughts.
<Okay>
1.5" drain and the 2 outer 1" to drain into sump. That would put approx 2200ish gph into sump.
<Uhh, no... about half this at most>
So first question is with 5' of head, what should my return pump be rated at to handle that.
<I'd stick with about 1,000 gph maximum calculated>
Internal, external doesn't matter. I would run 1" return line back up T'd off to separate 20g fuge(this will gravity feed back to sump return area). The 1" return line would T off again up near tank and drop back over the top into tank.
The other 2 1" drains would T together up to 1.5" to feed into Dart pump for closed loop. I would run the dart up through a OM 4-way, 2 returns would come up over the top to the front corners with loc-line, the other 2 would come over the back of the tank, run along the very back inside the tank to the bottom middle on each side and come back up through the sand with more loc line to generate flow back up. I have to run the lines through the tank as the bottom is tempered and can't be drilled. The goal is to have no powerheads anywhere in the tank.
<Will, can be made to work.>
I am sure there is something I'm missing in here, so any help is appreciated.
Thanks,
Brian
<Just "missing" the estimate (of probable gravity/drain feed from the 1.5 and 2-1" lines) and need to consider the return in turn... all else reads as fine. Bob Fenner>

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.>

Combining Overflows/Refugium Substrates 2/26/08
Greetings WWM Crew,
<Hello Bart.>
I have always enjoyed the hours I have spent reading on your site and the valuable info you provide. For this I offer my thanks.
<Thank you.>
I have a few plumbing questions for you regarding a system project I am undertaking. After three years of successful reef keeping in my 72 gallon bow-front I have acquired a pre-drilled AGA 120 and am making the switch. I am especially excited to do away with my siphon overflow (no major mishaps...Just lucky I guess).
<I hear you my friend!>
I will keep a variety of LPS corals on about 120 lbs of liverock and stock fish very lightly.
The tank is pre-drilled with two Megaflow overflow chambers installed. They have the standard 1" drains with Durso standpipes and ¾" returns. I understand from my research here that these are smaller than is to be desired, but my thinking is that I can get healthy water flow if I add some big powerheads in the tank and take care of filtration and skimming in the sump with the 12 or 1300 GPH I will get from the twin drains. Is this reasonable to assume?
<I am sorry, but no. These are smaller than to be desired, a 1” bulkhead will only flow around 300 GPH safely, giving you around 600 GPH total draining capacity.>
My plan is to place a 50 gallon sump in the basement, directly below the tank. If I were to combine the two 1" drains into one 2" pipe, will my drains slow down?
<This will work fine, the 2” has about 4-5 times the draining capacity as a 1”.>
I'm thinking it would be easier to send one pipe through the floor than two. The sump will be a simple design and house a skimmer (not selected yet) followed in line by a refugium. The return pump will be an IWAKI MD70RLT which should be able to handle return flow approaching 1400 GPH at the required head.
<You will want to choose a smaller pump.>
Since the combined flow to the sump directly below the tank should be around 1200 GPH, would this be too much flow for a refugium housing only Chaetomorpha?
<No, that is fine for the Chaetomorpha, but you will not be flowing this much.>
I am considering a sump with no substrate because I have heard that the substrate can become a nitrate factory. This is confusing because I have also heard that Deep Sand Beds are denitrifiers. What are your thoughts regarding refugiums without substrates?
<I like and use the DSB method. Substrate can become a nitrate factory when it traps excess detritus, usually a trait of large grain substrates. The use of fine substrates will not be an issue and will benefit your system with proper water flow, which you will need even if you leave the refugium bare bottom.>
My plan is that the Refugium and the skimmer would be the ONLY filtration in this tank.
<And the live rock in your display.>
I thank you in advance for any help you can offer. Keep up the good work!
Bart
<Welcome, will do. Scott V.>

Doing an Overflow "Calfo" Style 2/23/08
Hello Crew,
<Good evening.>
I've been reading and searching on WWM for my question to "Calfo" style overflows but can't seem to find the answer. I'm installing an overflow in the back of my 90 gal tank which has been drilled for two drains. Both drains are using 1 1/4" PVC attached to 1" bulkheads running to the sump.
<OK>
Due to space limitations where the tank is located the bulkheads for the drains are reversed ( flange on outside of tank) allowing the plumbing to fit closer to the tank. Thus this places the longer threaded end of bulkhead inside the tank.
<Not a problem.>
The bulkhead and PVC down elbow protrude approx 3 1/2" into the tank. If I install a "Calfo" style overflow obviously it will have to be at least 4 1/4" wide to allow for removal of the elbow if necessary but the question I have is how deep does the overflow have to be? How much water should be inside the overflow below the level of the drain bulkhead?
<You will want the inside bottom of the overflow to be at least 1 ¼” from where the water will enter the elbow in this case. This will allow unrestricted flow into the elbow. You can go deeper if you like, but it is not necessary. You may also be able to trim the bulkhead and elbow down a bit to get the width down a little.>
I was going to purchase an overflow that I could drill and attach to the bulkhead fittings but after some consideration on the hefty prices of the commercially available overflows, I'll make mine.
<I do sell overflows and do always encourage people to make their own whenever they are comfortable doing so.>
Any input on design considerations for my tank is greatly appreciated.
<It sounds like you have the right idea and a good plan. I will give you one tip from experience: If you do not go all the way from one side of your tank to the other, do be sure to leave enough room between the overflow and the side to fit in a magnet cleaner! It is all the small things that make life easier.>
Keep up the outstanding support.
<Will do, thank you, Scott V.>

Overflow Options 2/15/08
Dear crew,
<Hello James.>
I currently have a 300 gallon acrylic tank. 96x24x30 with two overflow boxes, 5x6 inches in each corner. I was planning on putting 2in bulkheads in each, but I can’t fit the 2in Durso standpipe in that narrow box.
<Bummer.>
I’ve trimmed the elbow and tee down so the standpipe now barely fits in, but I would have to drill the hole very close to the seam. I’m trying to get 3000gph through the tank.
Question#1 Should I get rid of the standpipe so I can keep the 2incn drains in the overflow box fairly centered and away from the seam.
< With this much water being moved it will be quite noisy without some sort of standpipe.>
Question#2 should I use the overflow boxes for the 11/2 returns and just drill
the back for 2-3, 2inch drains?
<If you are set on running 3000 gph through the sump then this is your best option.>
Question#3 If I drill the back, how far below the top seam would I have to drill for the 2inch bulkheads.
<I assume you intend to drill the back inside the overflow box? This will allow you to fit an inverted elbow inside the box to quiet things down. As for height you will want the top of the bulkhead to be a few inches down from the top of the overflow. Go too far down and you will hear the water falling inside the overflow. If you planned on drilling outside the box your height will depend on how you plan to set the drain up. If you just plan on running an elbow inside the tank you should drill fairly close to the top, but leave at least one hole diameter between the hole and any edge. If you plan on building a box for the overflow, then the same recommendations apply as above for the built in boxes.>
I would greatly appreciate your advice and opinion on this matter, thanks
james
<Welcome, good luck, Scott V.>

Horizontal Overflow 2/8/08
Hello!
<Hello Mike.>
I have a 75g tank I would like to use with a sump setup for an African Cichlid tank..
<OK>
I would like to try the "horizontal overflow", however, I'm not having a whole lot of luck finding any "standards" to go by for what actually "works best", such as, length, width, height, how far below the waterline you should place it, optimal bulkhead depth, (2) 1" bulkheads, or (1) 1 1/2" bulkheads?
<Nor will you…there are no such standards. Each individual application is entirely different/custom. The size of the box/weir will be dependent on how big you want it. As far as waterline it may take some trial and error. This aspect will depend on the size of the box you build and the flow running over it. If you run 1000gph over a 5”X5” box the water level is going to be higher than a 5”X10” box. The bulkheads are again totally dependent on your planned flow through them, but larger is usually better. As far as bulkhead placement, I would recommend you place the bulkheads as high up in the box as possible. If you place them too low you will hear the water as it falls from the top of the box down to the bulkhead’s level.>
If you could point me to some useful resources to help me in my planning, I would appreciate it.!!
<I build (and sell) a similar product to this. You can view my installation instructions in the link below to get some ideas regarding placement and size/flow. The general idea for your project is the same.>
Thanks for your time (and help)!
Mike
<Welcome, have fun, Scott V.>
http://www.momsfishsupply.com/overflowinstallation.html

100g Tank Transit Volume/Overflows 2/4/08
Hi Bob,
<Hello Lewis, Scott V. with you.>
The website is great but I was wondering if you could give me some advice about my current situation.
<OK>
I have a 100g tank given to me for free that was drilled with 2 x 1 inch holes at the waterline. I have a 500 GPH pump returning water from my sump, but because of the head, this is about 250 GPH. I would like a reliable method (ie. power cut tolerant) of draining water from my tank to my sump, without flooding. I know you have recommended 6 x 1 inch holes for a 180g in the past, but I can't drill my tank. I currently have a siphon set up, controlled by using a tap on the 32mm drain, but this is not practicable long term, as in the event of a power cut, my tank would drain about 15g into my sump with a total capacity of about 10g. So, which parts of my setup need I change/add? Many Thanks in advance! Lewis
<Your issue here is the transit volume, that is how much water is above the overflow, in the lines or gets siphoned out via your return line when the power is off, not the overflow itself. You may be able to lessen this by positioning the return line output directly below the water level in your tank or drilling a siphon break in the line. The transit volume will always be there, as a certain percentage of the tank volume, so it is likely you will simply need a larger sump for a tank this size. A note on the overflows, your 2X1” will easily handle the flow you are running and be far more reliable than the siphon type. Welcome, good luck, Scott V.>

Enough "fall" for Overflow 1/6/08
Crew,
<Ben>
Thank you in advance for you response. Before I go hole sawing through my living room wall, I thought I better run this by you. I'll try to ask this in a clear concise manner, but bear with me.
<OK, no problem.>
I have a 240gal. "through wall" set up, as in the display with stand & canopy is in one room, and everything else (sump etc.) is in the garage behind it. My concern is that the sump sits on a 30" high table and there might not be enough "fall" for the return lines. I have no experience with hydrodynamics, but do know that this depends on how much & over what distance, so here are the specifics. I have 4 X 1.5" drains drilled along the top back wall of the tank. My return pump is doing 2460 gph with my manifold configuration as is. (I've tested it several times) The drains, however, will only have about 10" of fall over a 10' span. Is this enough to keep up with the pump?
<Should be, 615 gph per 1.5” bulkhead.>
<<Mmm, what re the horizontal run? This may have a decided impact. RMF>>
I'm thinking that because I have some overkill on my drains, that I should be okay.
<The more the better.>
I guess the question boils down to how fast does water move downhill?
<The problem won’t be the 10” drop (you are not siphoning), it will be the 10ft run, that does decrease flow somewhat, but you will be fine here.>
I hope I made this somewhat clear... Any help would be appreciated. Thanks,
Ben
<Very clear Ben. Sounds like you are on the right track. Have fun setting up, it is one of the best parts of reefkeeping, Scott V.>

Re: FOWLR Setup for Messy Eaters 1/4/07
Thanks Scott for the response!
<Happy to help Brian.>
I was looking at drilling tanks and found that drilling tempered tanks (by me) may not be the best idea. I'd rather not have a glass "sculpture" in my
living room. (Maybe I can sell it off for millions as contemporary art?).
<The bottom is likely tempered. Do check with the tank manufacturer if your back is tempered, chances are it is not. You can overflow through the back too. If you find a buyer for such art, please let me know, I have many old tanks I can bust up!>
I was looking at hang-on overflow boxes. Would these work in conjunction with the LR to keep the water clean with messy eaters in it?
<It would work fine.>
I understand these work by suction, so it would be prudent to have 2.
<Highly recommended to have redundancy with these and any overflows.>
Do overflow boxes come with a GPH rating?
<They should, but the bulkhead the box uses on the backside is usually the true limiting flow factor with these boxes.>
How should I match it up with the return pump GPH rating?
<If you have two boxes, there will be nothing wrong with matching the pump’s flow at the head height you have to the full flow capacity a box/bulkhead. This will leave you with each box being able to handle the pump’s flow should the other box fail.>
For example, should one be higher than the other?
<If anything, have the pump flow less than the box/bulkhead can handle.>
Or should I just use a variable ball valve to balance everything out myself?
<If you get a larger pump than needed, you will need to. Don’t try to balance the flow right on the verge of what the box/bulkhead can handle. Leave yourself some margin of safety for things getting partially plugged.>
Scott also mentioned a filter sock. Is this just like what it sounds? A sock placed somewhere where water gets forced through it trapping particulates?
<Yes, usually the overflow line is dumped into the sock hung on the inside of your sump.>Thanks again guys! You've been very helpful!
Brian learning a little bit.
<Welcome, keep reading and learning, have fun, Scott V.>

Questions Regarding Overflows…(Another Unrealistic Expectation) – 12/26/07
Dear Crew,
<<Hello Brian>>
Hoping this correspondence finds all you fine ladies and gentlemen in good health, and enjoying a happy holiday season.
<<Mmm, funny you should ask as I’m still getting over a rather nasty bout with the ‘crud’ for the past 8-days … Not how I had hoped to spend my vacation...but happy nonetheless to be starting to feel “human” again. Thanks for asking! [Grin]>>
My question today is in regards to providing adequate flow through a 75 gallon reef system.
<<Okay…and I’m sure you’ve already read through our more than ample information on the subject>>
Rather than buying a grossly under achieving "reef-ready" system,
<<Hee-hee! I guess you have!>>
I've decided to go the route of purchasing a standard 75 gallon aquarium and having a go at drilling it myself.
<<Goodonya mate! Not such a tough task if you’re a bit handy…just be sure you get a tank that doesn’t have “tempered” panels where you plan to drill! Generally, on a tank of this size only the bottom is likely to be tempered. If purchased new, the manufacturer should have any tempered panels labeled as such…but it doesn’t hurt to contact them to be sure, especially with older/used tanks (assuming you can identify the manufacturer, of course)>>
After reading through the various FAQ's regarding overflow plumbing, and seeing the high praise and feedback that glass-holes.com have received, I'm inclined to go with their 1.5 inch through-the-back overflow system.
<<Okay>>
Per their website, they indicate that this should accommodate up to 1500 gallons per hour.
<<Hmmm, looks to me like this setup features a single 1.5” bulkhead…750gph is a more realistic expectation here, as well as a much more manageable flow rate re noise/sump plumbing simplicity>>
For safety's sake, I'm considering adding a second bulkhead/overflow to provide for a backup in the event that a blockage should occur.
<<Redundancy can be a life saver...>>
Since this is a system that is not dependent upon a siphon for facilitating the overflow, am I correct in assuming that any return pump should work provided that the rate does not exceed the overflow capacity?
<<That is correct…the return rate will match that of the pump rate…assuming, as you correctly stated, that the overflow rate of the throughput is not exceeded>>
The way I see it in my mind, the rate of the return pump would dictate the amount of water that would flow over the lip of the box, correct?
<<Correct…and thus you are likely also aware the “height” of the overflow box helps in determining the “running” height of the water in the tank…something to be considered when positioning the box>>
Sorry if this seems like a silly question, I'm just preferring to err on the side of caution as I only plan on doing this once.
<<No worries mate, well understood… Do be sure to plumb a gate-valve on the output side of the pump to temper flow if needed>>
Many thanks for your collective continued efforts,
Brian
<<A pleasure to help, do let me know if I can be of further assistance. EricR…back with the living>>
ScottV chimes in:
<The Glass-Holes.com kit mentioned does indeed include two 1 ½” bulkheads. It is actually the kit shown in the video on the same page. The picture/listing is generic…I will remedy this. Sorry for the confusion, Scott V., fellow crewmember and a partner in Glass-Holes.com.>

Re: Questions Regarding Overflows…(Another Unrealistic Expectation) – 12/26/07
Eric, Scott,
<<Brian>>
Many thanks for the clarification, and again for the excellent advice.
Cheers,
Brian
<<Ah yes, I am glad Scott stepped in to clarify/correct my perception of the "kit"...don't need any added confusion. Good luck with your project. EricR>>

Drilling overflows in AGA 12/16/07
Crew,
<Hello David.>
I just ordered an Aquarium Glass Diamond Hole Saw Kit from Diamond Tool King who advertises as one of your sponsors. I already paid for the purchase through PayPal. Do you know if Steve @ Diamond Tool King is legitimate? His prices are excellent, which sort of scares me. I hope his being one of your sponsors, or his advertising on your pages shows he is legitimate.
<No worries, the bits will work fine.>
Here is why I am ordering from him. I am setting up a reef tank starting with a 120 gallon AGA tank. I keep collecting pieces and parts, and reading and continually Reading and rereading. Sorry to say I did not find out about your site until a few weeks ago. I have now repeatedly read that the bulkheads holes are to small too begin to consider the tank a "reef ready Tank".
<Unfortunately the case.>
Yes I will, after tank aging, use the tank principally as a SPS tank, with a small scattering of LPS and even less soft corals. To date I have obtained two Iwaki 40RLXT's, Turboflotor 1000 with Ocean Runner 2700 pump for skimming, Aqualight Pro with two 250-Watt 10,000 K and two 96-Watt PC's. I also have a Megaflow Model 4 Sump, which had to be trimmed to even allow for the TurboFlotor. If I had known that drilling bulkhead holes was not such a great task I would have never gotten the MegaFlow sump. I might still replace it with a glass aquarium and place the baffles where they will work best.
<Whatever it takes to suit your setup, drilling the glass is fairly straightforward.>
I do not plan on using the Bio-balls that came with the sump so it might workout OK. I plan on about 100-150 lbs Live Rock some thing from at least three different areas. Probably large Fiji rock, Tonga shelf and branch rock and some other exotic rock. Now for questions and suggestions. I plan on cutting out the AGA overflow boxes and plugging the small bulkhead holes with plugged bulkheads. Yes I even footed the stupidly high price for two Megaflow overflow kits. Learning can be expensive!
<Learning generally costs something, whether it be time or money!!>
Anyway I plan on two 3 inch holes for 2 inch overflow bulkheads on the tank's back wall, giving a space of at least 3-3.5 inches between hole edge and tank inner wall. Top of 3 inch holes about 2 inches below tanks glass cover ledge.
<Sounds good, perhaps a little bit lower. General rule of thumb is one hole diameter away from any edge. Two inches down should be fine, but three will give you that much more strength in the end. Good choice on overflow size, plenty of capacity here.>
The return locations I am not sure of. With the tanks present setting viewing will be almost entirely through front wall of tank allowing me free rein to drill return holes in side wall which I believe would create better turbulent flow
possibilities due to the opposing flow from returns at both ends of tank. What do you think?
<I am not a fan of drilling for sump returns, at least not too far down due to siphoning issues.>
What with live rock, crushed coral, and live sand/gravel (from GARF) displacement eating up probably 20 gallons of space I figured targeting 2000-2100 gph for flow would probably be acceptable. Shouldn't be able to get around there with my two pumps returning through 1 inch PVC pipe and 1 inch bulkheads.
<Yes.>
I really don't know what would be optimum location for return bulkheads, ie. where on side walls. Middle of front to back? How far from top edge. How did I prevent back siphoning if pump power is loss.
<Yes, this is the problem. Some rely on check valves, but these are not to be trusted to work 100% of the time.>
I also have two Pan World pumps with 1 inch inputs and outputs that I could use for running circulation loop(s) or possibly throttling down one for use with a AquaC EV series skimmer if the TurboFlotor does not work out.
<A closed loop is the way to go here. You will be able to put the intake/return(s) where you would like to optimize flow (perhaps even use the predrilled holes for the intake). This will also allow you to run whatever flow through your sump you desire rather than running the tanks full circulation through.>
I also have a 1/4 HP chiller, lots of Maxi-Jets (900'sand 1200's) and two Wave Masters. Think I need to sale some circulation heads and wavemasters.
<It always seems like you can never have too many extra utility pumps!>
Is there any reason I should even consider putting return bulkhead holes in the tank backwall?
<Over the top will be fine. If you want to drill consider putting it fairly close to the top (again, at least one hole diameter from any edge) and use some Loc-Line for adjustability to minimize siphoning.>
Opinions and suggestions please, before I start drilling, that is if the diamond hole saws show up. Sorry this is so long, but I only have three weeks before school starts up again and I am really antsy to get started on this tank when I am not working.
<Nice project to work on with time off.>
Its been over six years since I last had a reef tank and things seem to keep getting better as time goes on. My last tank was a 125 gallon with a "high" turnover rate of 4 times per hour, 2 Maxi Jet 900's, a 20 gallon sump, 3 250-Watt 650 K halide shop lights, and a Kalkwasser drip. No skimmer, auto top off, CO2 calc reactor, hood with double ended halide bulbs, Actinic Power Compacts, LED moonlights. Things do change!!!
<Wow! They sure do.>
Thanks,
David E. Harris
<Welcome, have fun with your project, Scott V.>