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FAQs on Undergravel Filters, Filtration

Related FAQs: Biological Filtration, SW Use of Undergravel Filters, Deep Sand BedsFluidized Beds, Ammonia, Nitrites, Nitrates, Phosphates, Fluidized Beds, Ammonia, Nitrites, Nitrates, PhosphatesDenitrification/Denitrifiers, Deep Sand Beds

Related Articles: 5 Pros, Cons of Undergravel Filters, BioFiltration, Plenums,

UGF Alternatives Fish Only 4/23/2009
Good Morning Crew!
Many thanks to all of you, I have been very happy with the site and all the advice.
<Thank you for the kind words.>
I am looking at changing the filtration for my 55 gal. tank.
I've gone out and bought a protein skimmer, which I haven't set up yet.
<This will go a long way towards improving water quality.>
I am considering abandoning my UGF. I know from research that when maintained properly they can be very effective and easy filters to have and I've since changed my die hard perspective on they're 'un-cool-ness'.
<They have their advantages and disadvantages. Overall, there are much better alternatives out there though.>
I believe I would be much better off converting to a FOWLR tank.
<I agree. There are many advantages to converting to live rock>
I find that the plates get caked with detritus easily. I must confess that I work long hours and I am not always able to take the time to clean the plates properly. As a result, my Nitrates and phosphates stay higher than I would like.
<Not surprising.>
I have been doing small water changes, and completely cleaned the gravel which is about 3-4 inches deep,
<Do try to change 10 - 15% per week.>
What I'm having trouble with is all the options I has in converting and I don't know what would be best. Should I remove the plates completely, cap them and leave them, or just clean under them and replace them. I believe this to be the least traumatic. I've used this filter for as long as the tank has been running and I'm comfortable with it. I've gone through your site, and read the articles, such as the pros/cons of UGF by Bob.
Any advice you could give would be a big help.?
<Hmm, for a setup like this, I would clean under the plates and cap them off (just leave them in place). Add cycled live rock, about one pound per gallon of water in the tank, and get the skimmer running as soon as
possible. Additionally, if a sump or refugium is not practical, I would look into getting a canister filter for mechanical and chemical filtration, and adding a power head or two for additional water movement.. These,
along with regular water changes, and you will see a dramatic improvement in your water quality and livestock health.>
<Best of luck and do send a follow up when you get your new setup>

UG Filtration use And Sand Sifting Starfish fdg.  2/22/08 Hi, <Hello Richard> I have a 200L tank which currently holds 6 Hippocampus kudas and a Blue Linckia (plus a handful of small critters thrown in for good measure). I'm filtering the tank through an undergravel filter combined with an external canister filter on one of the UG uplifts (the other two are just running on air). <The UG may/will cause big problems for you down the road. Do read here. http://www.wetwebmedia.com/FWSubWebIndex/ug5proscons.htm> I'm fairly new to a marine setup, having come from the freshwater world where I always ensured that I had something in the tank which rummaged through the gravel to remove the bigger particles & stop calcification. I don't have anything in this tank however to do that, so I'm looking around at what I can get for the job. I was considering a Sand Sifting Starfish, but I'm concerned that I'll end up having some kind of issue with the filtration (although I imagine it's not going to eat the filter - I hope! - or stop the bacteria working). <This would be a good addition in keeping the substrate churned. Keep in mind that the substrate should be coral sand. Crushed coral and the like isn't going to make the starfish very happy.> Any thoughts on this? I've read up in a few places about these starfish, but never in relation to UG filtration. <As long as the "sand" bed is 1 1/2" deep or more, you should be fine in keeping this starfish. It may require additional feeding if enough nutrients aren't available. I have one myself and whenever the starfish exposes itself for any length of time, it's telling me it's hungry. My trick is to use a syringe minus needle, and inject blood worms into the sand just below it. Believe me, it doesn't take long before the starfish buries himself and starts munching on the worms. Must have a great sense of smell.> Many thanks in advance, <You're welcome. James (Salty Dog)> Richard

Re: Undergravel Filtration And Starfish 2/23/08 Hi James, <Hi Richard> thanks for the reply. <You're welcome.> The substrate I'm using is 3mm crushed coral, so I guess the starfish is ruled out. Any suggestions on alternative cleaners? <Mmm, probably the Nassarius and Cerith Snails would be your best bet, the Nassarius being the better for eating waste/detritus as they often burrow into the substrate searching for food.> I've read the link on UG filters (even quoted it). Before making the jump from freshwater to marine I never really had any issues, as long as I had something in the tank which regularly churned the gravel (loaches were especially good for this), which is what I'm looking for now. Certainly it's my feeling that an UG filter is better able to absorb a spike in ammonia. <A wet/dry trickle filter would be my choice. If the substrate isn't maintained (gravel siphon) on a regular basis, a nitrate factory will soon develop sharing real estate with a hydrogen sulphide plant.> Also, the filter canister (440L/hour) is drawing through the UG which gives a nice final filtration/backup. This was probably the best info source that I found: http://www.syngnathid.org/ubbthreads/showflat.php?Cat=&Board=FlatMates&Numbe r=53935&page=0&view=collapsed&sb=5&o=&fpart=1 <Led me to the home page with errors.> To be fair, it does kind of show the starfish in a crushed coral base. <Much easier for them to move around in a sand base than 3mm (1/8") gravel.> Thanks & regards, <You're welcome. James (Salty Dog)> Richard

Broken Underground-Filter Pump On 30g Marine Tank - 02/18/08 Hi there, <<Hello>> I was wondering if you had any advice on what to do if your UGF pump breaks, and all the shops are closed? <<Hopefully you have a spare air pump and stone lying about… Remove the pump and place the airstone at the bottom of the riser-tube (just like the "old" days). The rising bubbles will move water/keep your filter going until you can replace the pump>> Will my tank be OK for 12 hours without water movement? <<Not recommended… If you don't have an air pump (can even be used without a stone if you don't have one), I would at least stir/agitate the surface of the tank water periodically to allow some gas exchange>> Is there anything I can do? <<As stated…and keep a "spare" powerhead on hand from now on [grin]>> I have a 30 gallon tank with 2 clowns, a blenny, a cleaner shrimp and a red legged hermit. <<Do consider a "better" filtration method for your tank. Much to read about here (http://www.wetwebmedia.com/marine/setup/filtration/marineFiltr.htm) and the associated links in blue at the top of the page>> Thanks for all your advice, love your page. <<Hope this helps. Please read through the links and feel free to write back to discuss alternate filtration methods for your system if you like. Eric Russell>>

Under-Gravel Filter in My Marine Tank - 10/02/06 This is a phenomenal source of information and I appreciate it greatly. <<We're pleased you find it of use>> I have become accustomed to using your site to answers all of my questions about my tank needs.  I have a question about the UGF. <<Under Gravel Filter>> Upon reading I discovered that this may become a potential problem in the future with nitrite build-up. <<Does promote the trapping of detritus in the substrate (could go with "reverse-flow" I suppose), but just how problematic it becomes depends greatly on the type of marine system I think.  Though I did it 30 years ago, I wouldn't set up "any" marine tank these days with a UGF.  I much prefer to use live substrates/live rock for bio-filtration, and in the case of a FO or FOWLR system, supplementing with a fluidized-bed filter when/if necessary>> I have also read differing opinions about what to do to eliminate the problem of the UGF. I have read a lot of advice, but I would like to hear what you have to say about my specific application. <<Sure>> Here are my questions: Should I remove my UGF plates or cap them and leave them in place? <<You can do either, though obviously the latter is much less work/causes less disturbance of the tank.  It's up to you but I would probably just remove the uplift tubes and let the substrate "fill the holes">>>> Is there an advantage to completely removing the plates or just capping them? <<Mmm, depending on the depth of the bed...the first may temporarily disrupt essential biological activity...the second will not>> Does removal cause any diminished effect to filtration in the tank? <<There will be a change in types/stratification of bacteria due to the decrease in oxygenated water drawn through the substrate...but a change for the better in my opinion>> Should I leave the powerheads in the tank for circulation and just place them in the Fiji LR? <<Yep>> Can you over filtrate a tank? <<Depends on your definition re, but yes, many "reef" systems suffer from excessive nitrogen depletion so some extent.  But for the most part this can be dealt with and is preferable to the opposite situation...I don't feel over-filtration need be a concern>> This is a side question about placement of the pick-ups for the canister and protein skimmer.  Should I place the pick-ups on the opposite side of the tanks of try to put them in the center?  I have the Mag3 in the middle, but the Eheim is on the left side of the tank. <<This is fine...whatever is easiest to hide/most aesthetically pleasing>> Tank Facts: 55 Gallon Tank 1 - Eheim Professional II 2026 <<Cleaned weekly I hope>> 2 - Zoo Med Power-sweep 214  160GPH 1 - AquaC Remora Pro with a Mag3 Drive 55 lbs of Live Fiji Rock 50 lbs of Florida Crushed Coral (about 2 ? inches deep) Tank is four months old 2 - Clowns 1 - Huma Huma (I know about size, 150 Gallon is coming in summer of 2007) <<Ah...good>> NO3 Level - 0 NO2 Level - 0 pH Level - 8.0 Ammonia - 0 Thank you for your expert information and website. <<We're happy to share.  Eric Russell>> Scot Wattawa M.Ed., A.T.C./L Dinosaur marine undergravel filter - Hey, if it works! 11/1/05 Bob. after reading several opinions from your website, it seems my undergravel filter system is out of vogue according to several experts. <Heee! Define "vogue", "experts"...> I have had this setup (twin filter plates in 55 gal tank, 2 powerhead 400's in back corners, a Skilter 400 skimmer/filter system and full length Coralife lighting). I don't want to remove my filter plates if possible. Would blocking my uplift tubes or a reverse flow system be better alternatives? <Yes... would create what "modern experts" call a plenum> What precautions should I take be bore converting to either method? <None really... could perhaps add a bit more substrate. Please read here: http://wetwebmedia.com/Plenums.htm and the linked Related FAQs at top. Cheers, Bob Fenner> Sincerely, Randy Stewart  

Advice on Marine UGF  9/28/05 Hi guys (and gals), greetings from England. <Mmm, am from Rhode Island... often confused with Mars> My question mainly revolves around the UGF and gravel that I was mis-sold by my LFS (Have recently changed due to the bad advice given by said LFS). I have had a Marine tank set up for 6 weeks now ( it's my first) that I want to run it FO and then once it matures (and I become confident in my husbandry) introduce some inverts. It has cycled already (NH3, NO2, NO3 all at zero after rising and falling) Here is the spec: 150 litres (48"x12"x18") 3Kg Fiji LR (Couldn't afford any more!) and lots more base-rock that'll hopefully become seeded Fluval 4Plus Internal Filter UGF with 2X 600litres/hour Powerheads attached to 1" uplifts 1.5 - 2" gravel (not sure what this is called - see attached picture. The grains seem to be 3mm - 5mm on average with a few crushed shells etc - any idea what this is?) <Coral... coarse sand, rubble... natural product> 1 Marine White NO Flour 40W 2 X Marine Glo (Blue) NO Flour 40W (soon to be replacing one of the blues with a Marine Life) Some Caulerpa that came on the Live Roack Various bristleworms, copepods and spaghetti worms A sump is not really an option (I know you guys favour this!) <You've been reading> My plan was to buy a Protein Skimmer ASAP (next week) and get this up and running, adding more live rock (curing it as I get it of course) as I go as I cant afford to get it all at once. I was also going to add 2 Ocellaris clown this weekend and see how I get on with these for a couple of weeks before adding any other livestock. <Okay> My main concern now is that the UGF is going to act as a Nitrate factory so I'd like to "replace it" with something more appropriate. I don't really have the option to go out and buy another 20Kg or live rock due to money restraints (I will be buying more over and extended period of time though) so was thinking instead of using a canister filter such as a Fluval 304 or similar. Would this be a good way to go? If I then replaced my existing "gravel" with a DSB of 3" of super fine sand would I eventually be able to do without the 4plus internal filter as well? I have assumed from reading your articles that the existing gravel (see picture attached) is totally unsuitable for a DSB. Would I absolutely need to remove the filter plates when using the super-fine sand? <Mmm, well... you could just wait here... less disruptive... and take out the plates later... better to focus on your added skimmer, live rock at this point> Assuming it would be best to do this before I put the Clowns in, how long would I realistically have to wait after replacing the substrate before I put them in? Any help would be greatly appreciated. I have read most of the FAQs in this area, but cant really make sense of my predicament! (Conscientious Marine Aquarist is on its way via Amazon!) Cheers, Chris. <Ah, yes. Know the author. I would leave all you have as is for now... not too many years, places ago, your set-up was the standard approach... Can/will work... with a bit of extra maintenance, less margin for "errors". Cheers. Bob Fenner>


Undergravel filter still in use Hello Folks, Very glad to have you here as I've received different answers to my question(s) (not all that surprising though). The tank in question is my 45g mini reef, which was a slow conversion from a 15yr marine tank. The big question is when the tank was new it had what was then the standard filtration, under gravel w/ power head.  Currently for filtration I have Bio-wheel, LR, skimmer, PH.  Am I wrong in thinking that if I remove the lift tube I will have a pocket of "dead" water under the substrate? <Mmm, nowadays called a plenum... see here: http://www.wetwebmedia.com/PlenumFAQs.htm> I like the extra filtration, but I would also like to not see the lift tube.  Lastly I feel it would not be wise to disturb what is a happy healthy tank by removing the under gravel base. Opinion please? <Can be done with little chance of real trouble if the tank is not "too dirty", crowded, over-fed...> Sorry if this has been asked before, but I did search first. Yours (with wet salty hands) Greg PS sure is fun to be in a heat wave in Vermont-glad I have that freezer stocked with lots of frozen sea water bottles! <Yes! Bob Fenner, just back from balmy (99 F.) Chicago and Minn. layovers at the annual IMAC conf.> Plenum Vs. UG Filtration 4/1/05 Howdy Bob and Anthony. <Howdy> Anthony, I've received and read your book. Marine life is simply amazing isn't it? I have ordered your and Bob's book of reef inverts. Can't wait. <Thanks kindly!> Well, as you have both told me, I am actually running an undergravel filter instead of a DSB/Plenum (I assume due to the risers and powerheads). 55 and 33 gallon tanks. Question is, I am re-vamping my 90 gallon for my farming project and would like to know the benefits of true DSB/Plenum vs. UG DSB/plenum systems. <Ahhh... When the "Reef Invertebrates" book arrives, you will have our current opinion at great length... about 100 pages on live sand, DSBs, refugia, plants and algae!> (90 gallon used to have 4"crushed coral bed and Nitrate levels off the charts :() My UG tanks are actually doing quite well, except the pH will not stabilize higher than 8.1, buffered every day.  Simply put, would you recommend DSB on bare glass, DSB on plenum with no risers, or DSB on Plenum with risers? <A static bed on bare glass is fine> I am open to any of these, I do love the looks of the DSB. I want a pH of 8.3, as I would like to do mass Xenia production in this tank. Does the rapid denitrification process of the UG/DSB really hurt my dreams of 8.3 pH, or should this be possible in time? <On the contrary... DSBs support Ca/ALK, and pH> GARF suggested the UG/DSB/Plenum, but advised removing risers at later dates. <It's a waste of time IMO> I have read article after article regarding this matter and everyone has different ideas. <Mine are backed up with the use of 48,000lbs of oolitic sand, 5,000-8,000 galls of saltwater, and over a decade of experience FWIW> I believe you and Bob come across as having the most knowledge of all who I read from on this subject. (No offense to WWM crew of course) BTW, I chopped the heads off my mushroom Sarco only to find the insides rotten. <Ughhhh! Sorry to hear it> All frags doing great, but the mother colony has these little brown "bugs" crawling around on the freshly cut stumps. I left 1 head and cut 2 heads off. All frags and momma head doing great visually. Should I be concerned with these bugs? <Its hard to say with a pic or better description than "bugs" <G>. They are likely no trouble> Broad question, I know, but these little guys are like the size of a "speck" or grain of sand. They do move around if I poke them. This is my broodstock tank and I want to be careful here. Thanks for everything guys. Your pupil, Mike Toole Detroit, MI <With kind regards, Anthony>

FW substrate, UG filtration I got another question about filtration. I have a Magnum 350 and an Aquaclear 500 that are both fitted to my dual plate UGF (one on each plate, the magnum on the heavier loaded plate that Pacu hangs over a lot) with two normal bubbler tubes fitted with carb/ammonia. The gravel is both fine and large, but I left it rather thin. I thought this would work great for sucking all of the droppings down through, but instead every time Pace flicks his tail you can see how much of the larger stuff that isn't going through. Any ideas to solve this? <Better to use one grade of gravel... and about a given depth for UG filter use... Please read the Articles and FAQs on FW substrates and UG filters posted on WWM... they are indexed here: http://www.wetwebmedia.com/FWSubWebIndex/fwsubwebindex.htm Bob Fenner> Still Confused about UG Filters Hello, <Hi there> I'm a new marine aquarist, and I've been struggling along.  I've got a freshwater tank that has been very successful, only to find that marine is a different beast.  My tank has been cycled only for 2 months.  I've recently lost a few fish to ich (introduced a tang without quarantining first - AARGH!!!) before getting educated and figuring out how to address the problem. <Here's to progress!> I'm left to one clown, and it is in a quarantine tank getting medicated.  I'm planning on keeping it there for 4 to 6 weeks to make sure that the parasite in the main tank dies off.  I'm looking at an opportunity to make tank improvements, but I do have limitations: money and space!!!! <Coming to grips with the realization of ones limitations is my best working definition of maturity> I have a 46G bowfront, 3 feet wide and 2 feet tall.  I've got a 2" layer of standard gravel (sorry, don't know the proper name) and a 1" layer of CC on an UGF powered by two Zoo Med Oscillating Spout Powerheads (125 GPH).  I have a AquaC Remora skimmer on the way, which will be replacing my Skilter 250.  For lighting, I am using the standard issue fluorescent bulb provided with the hood. I've read many articles on UGF's, and that they will become a problem later.  Would it be beneficial to remove the UGF? <IMO, no>   I'm guessing I'll need something else to support the biological filtration, but what would that be? <Could be... a sump, refugium, wet-dry filter, canister, hang-on....> Are there any hang on filters that have adequate capability for biological support for this size tank? <Yes... could be used with the UG... these do work, but do have their downsides... principally more maintenance, difficulty I cleaning more as time goes by... but, all types, filtration gear do have their up/downsides.> I have a fish only tank and was really trying to avoid LR because of cost and lighting needs.  Any ideas?  Thanks for your help. Jim <Take a bit more time to read through WetWebMedia re filtration types, others experiences. At this point in your development, I would add one or two larger outside power filters (likely hang-on), and consider adding a sump/refugium, removing the riser tubes, but leaving the UG plates in place going forward. Bob Fenner> Removing undergravel filter Experts of WWM: <Hi Ron, MacL here with you tonight.>   I have recently been doing research about the removal of an undergravel filter from an already established FOWLR aquarium.  (I'm going to leave out all the useless details, of course.)  Anyway, the tank has been set up for a year and a half and all inhabitants seem to be doing well.  The U/G filter has turned into a nitrate factory, as I've learned they always do.  What I would like to do is to remove the uplift tube and cap off the plate.  I have only been able to find one instance (this site) of this being done, so I am extremely worried about doing this.  Anyway, that is my only question. can this be done without a die-off of aerobic bacteria, or cause any type of bloom? <Anytime you disturb your sand (or crushed coral or whatever bed) you will experience some die off.  You don't mention what other type of filtration you have, I'm assuming you have something to handle the filtration once you stop running the undergravel? That being said that you will have some die off the idea is to minimize the amount of die off.  If you can move the sand from around the tubes, then cap them then move it back without disturbing the sand or crushed coral in other areas you have a better chance of minimizing the effects. I think you should be prepared to do a water change in a couple of days regardless depending on the other type of filtration you will be going to. The way an undergravel filter works is pretty simple, it pulls the detritus down through the sand hopefully to end up under the undergravel where the bacteria attacks it. For this reason, once that water stops pulling down you are definitely going to have some changes going on within your tank.> Here are my tank specs: 30 Gal AGA, 96W PC 50/50, Prizm Skimmer with surface skimmer attachment, 40-50lbs live rock (40% Tonga, 60% Fiji), 2-3" crushed coral over U/G filter, powered by Penguin 550 Powerhead. <If you are going to try to go with the Berlin method where the tank is filtered by the live rock then you are going to need the power heads in the tank for oxygenation. If that filtration isn't already established this is going to become much harder to do. Meaning if you don't have bacteria built up in the live rocks and in the crushed coral. This may definitely mean water changes as the tank adjusts to the change.> The inhabitants include: Small yellow tang (to be moved to larger tank at later date), maroon clown, yellowtail damsel, bicolor Pseudochromis, scarlet skunk cleaner, 2 astrea conehead snails, unknown amount of margarita and abalone snails, as well as blue leg hermit crabs. <Ron I don't want to discourage you, I'm just trying to make you understand the reality of this undertaking.  Let me try to simplify a bit. If your tank is already being filtered in the majority by the live rock then a switch won't be quite so hard. BUT if your tanks primary filtration system is the undergravel then when that stops running you will have some changes take place within your tank.  You probably will have an ammonia rise but that can be handled cautiously with water changes in order to put less stress on your fish.>   Thank you very much, if only for simply reading this.. <I hope I have helped, if you wish to get into this discussion further or have any questions just let me know. MacL> -Ron Narozny, Jr. UGF viable for marine, or outdated? 9/17/04 Hi guys!  Wow, what a great site you have.  I've been out of the marine aquarium hobby for about 10 years now, due to space limitations, but am now looking to jump back in with both fins. <Adam here.  Thanks for the kind words, and welcome back!> I have been reading a few books and spending hours on this site, taking notes, and reading everything I can find related to a Fish Only set-up.  I have found a ton of valuable information so far, but one thing definitely has stood out as I've read the articles, and FAQs.  It seems that everyone on this site is dead set against using an UGF system. <You will find this opinion to be nearly universal among "modern" marine aquarists.  There is nothing inherently wrong with UGFs as your own past experience proves, but live rock and skimmers have proven to be much more stable and low maintenance.> For years, I had a quite small 35g Hex tank set up for FO, using UGF with only 1 powerhead on it, and was quite successful with it.  Granted, I stuck mainly to fish that were more tolerant of my small learning mistakes, but after my initial floundering, I had that system running for 3 years with no life lost.  I did biweekly water changes, that incorporated gently vacuuming 1/3 of my CC substrate each time.  Every couple of months, I would also do a water change/vacuum that included moving the larger rocks, cleaning under them, and giving the rocks a good rinsing in the water I was removing.  These procedures seemed to work very well for me (probably dumb luck), and now that I'm going to get back in, I was really hoping to be able to us UGF again, but now, after all my reading, I'm really wondering if I should. <Wow!  With a maintenance routine like that one, it is no wonder you were successful.  Few aquarists are so regimented and meticulous!> I know things have changed quite a bit (to say the least) over the last 10 years, and there have been some great strides in equipment that is affordable to the home hobbyist, but should we be throwing out the UGF completely?  I would like to tell you what I plan to set up (I have not bought anything yet), and ask if you think I am starting down the wrong road, or if I will be OK.  Here's what I plan to do: Aquarium - I'm looking at a 90g glass, but it is a little taller than the standard show tank.  I think the measurements are something like 48x30x30. I know the taller tank is not quite as good, due to a smaller surface area, but I have a smaller floor area, and the taller tank would allow me to get a larger gallon tank (which allows for a bigger buffer for when I make my mistakes), and take up less floor space.<This sounds perfectly suitable for a marine fish only tank.> Filtering - I WAS planning on using an UGF, a crushed coral base of about 4", with 4 powerheads (300 gph each), a HOT skimmer rated for 100g tank, and perhaps a nice long airstone on the back wall for a shower of bubbles. I like the looks of the bubbles, and if it's not going to hurt the fish, it will aid in water movement as well.  I plan to do the 1/3 substrate vacuuming (gentle and surface mostly) biweekly as I did in the past.  This should give me about 1,500 gph of water filtering/movement, which seems to be quite a lot for a 90g tank.<Your plan allows for plenty of water movement.  Be sure to research your skimmer choice.  Many manufacturers grossly overestimate the capabilities of their devices, especially for HO models.  The Aqua-C Remora Pro or Deltec HO are the only HO models that I would even consider for a 90 gal without doubling up.  If you do choose an UGF, the strict maintenance routine you described above should be followed.  Do beware that a properly maintained UGF will remain highly aerobic, producing copious nitrate.  This problem does not exist with Live rock and/or static sand beds.> Lighting - I am still not sure what to do here.  I know for sure that I want fish and a few shrimp and crabs only, no like coral etc, but with the taller tank that I'm looking at, I will need more powerful lights I think, but have no idea what power I should get.  Any suggestions here would be greatly appreciated. <The variety of options here is staggering, but since you don't plan on supporting corals, three to four standard output fluorescents or two to three VHO's should be plenty.  Actinic lamps, which are heavy in the blue spectrum will enhance the colors of many fish.> Live Rock - This is new to me, as I can't even recall this term from my foray 10 years ago.  I have done some reading on LR, and quite frankly, I like the looks of them in a tank, as there seems to be a lot of interesting critters on them.  With my proposed set up, would I be able to have a couple piles of the LR in my tank?  Is it something I should even consider, since I am hoping to use an UGF which most people don't seem to like anymore?  Does the LR require even more powerful lighting then, keeping in mind the taller tank? <You could use live rock with the UGF, but I would suggest using it instead.  A thin layer of substrate for looks (or a deep layer of fine calcific sand to aid in denitrification) along with live rock will easily replace the UGF in term of biological filtration, without the cleaning hassles and eventual clogging.  Lighting beyond what I recommended above is unnecessary to support most of the life on the rock.  I would however, recommend maintaining strong calcium and alkalinity levels to keep the attractive coralline algae healthy.> Fish - I would like to have a few clown fish (no anemone, as I'm not sure I'm capable of keeping one alive), a couple of small bottom feeder fish, as well as a coral banded shrimp, and a hermit crab.  For larger fish, I was hoping to have a couple of Bat fish, and my favourite one of all a Koran angel.  Do you think I would be going over my limit for this tank size/filter system with these potential pets?  I have raised all of these before with good luck, except for the Bat fish, which I intend to do some extensive reading on before I purchase. <Kudos on avoiding anemones!  They are possible, but much specialized care is required.  Your overall stocking level sounds fine.  Beware that sand sifting bottom feeders will not be very happy with coarse substrate.  They are much better served by "sugar fine" sand that is easily passed through their gills for sifting.  Pinnatus Batfish are wholly unsuitable aquarium subjects, and are doomed in almost all cases.  Other bats fair better, but rapidly outgrow all but the largest systems (several hundred gallons).> Any pointers you can give me at this point would be fantastic, as I would like to make sure I avoid the typical early set-up mistakes and bad choices, which can be so costly to fix/change after the fact.  I really would like to use the UGF (boy, I'm getting old and set in my ways eh?), but if you can convince me of my foolhardiness, I will get off that road, and look at other forms of filtering. <I am a big fan of "if it ain't broke, don't fix it.  If you found success with a UGF and your maintenance routine, who am I to talk you out of duplicating it?  I also maintained such systems way back when, and have found live rock systems to be much more forgiving and easy to maintain.  I personally have never looked back. Excellent resources include Bob Fenner's "Conscientious Marine Aquarist", and Delbeek and Sprung's "The Reef Aquarium Vol 1&2 (outstanding for both reef and FO systems).> Just so you know, a sump is not a possibility for me, so the only other alternative would be a HOT filter system I think.  Thanks in advance for any help you offer, and I really appreciate this site.  I think back 10 years ago, when there was no internet or chat rooms or helpful experts who answered your questions, and it's hard to believe I was able to keep any pets alive! :) Larry Coleman  <UGF or not, I would skip any type of HO power or canister filter.  They are an unnecessary maintenance chore.  If you feel compelled to use them, please do clean them weekly or more often.  Best regard and best of luck!  AdamC.> UGF in FOWLR Tank I recently sent a question regarding REVERSE flow with a UGF in a FOWLR and some soft corals and I tried to reply to your response to me from the "Crew" and couldn't...........the email came back undeliverable so I'd like to address/discuss this issue with you Dr. Fenner. <Just Bob please, I have no doctorate> I have a 75g in which I'm removing the deep sand bed...............too many problems I won't get into after 3 years. Anyhow, recently, while cruising a forum on another website (Reef Central), I came across a guy (Paul B=check it out on the site) who has had the same tank set up for 32 years utilizing a UGF with Reverse flow with 1-2 inches of dolomite.  I've been contemplating using a STARBOARD bottom until I came across this UGF set up used by this guy. <Neat... I finished an article a couple days back for a U.S. zine (TFH) on UGFs... so am a bit up to snuff on them...> Now...the response sent to me originally by your "crew" on my first email question( and I'll forward it to you separately) said that detritus and organics would get trapped in the substrate. But if you're using two pumps/powerheads like the Hagen with reverse flow at 170-200 gph, won't that blow the detritus and organics up off the substrate and into the water column which can then be removed by the skimmer or another form of mechanical filtration like an Eheim canister or Aqua Clear 500? You thoughts please. <With an in-line particulate/mechanical filter (like the canister) there should be little detritus to get lodged in the substrate with a reverse-flow UGF... what little there is will likely be digested, decomposed there. If the substrate bed is not too deep (depending on grade, shape, make-up...), regular maintenance will be able to remove "enough" of this accumulation. Bob Fenner> Don     

Re: UGF in FOWLR Tank So this is an ok idea?............should keep phosphates and nitrates low or to 0 with regular maintenance on the canister? <Not likely down to zero, but close enough with careful feeding, regular upkeep> What is your feeling about dolomite vs. crushed coral or even large particle aragonite.... <This is posted on WWM... most folks are/would be better off not using dolomitious (composite magnesium and calcium carbonate) materials...> again, only doing an inch to 1.5 inches or do you recommend a thinner layer? <Also posted on WWM... please read there> By the way, I forwarded the RC thread with the guys tank. Let me know what you think but please address my questions above .............thanks again! Don <Be chatting, reading. Bob Fenner>

Back To The Future? (Bare bottom Tanks And UGFs) Two questions: <Sure> Is there any benefit to using a UGF with reverse flow utilizing crushed coral as a substrate? <Well, reverse flow undergravel filters were all the rage in the late seventies and early eighties, before wet/dry filters and sumps came into vogue. They fell out of favor when more "complete" biological filtration systems and techniques came into being. UGF systems certainly are efficient biological filters, but they tend to trap detritus and organics over time, and will slowly drive down the pH of a system that employs them. In the end, you're really better off using the simple sump systems that are very readily available and easy to run> What are the pitfalls of a bare bottom tank? Don <Well, Don- in a nutshell, the real pitfall of a bare bottom tank is the lack of denitrification processes. I don't want to oversimplify things, but it essentially boils down to that. A sand bed-preferably a deep one- will foster denitrification processes that can greatly improve water quality. Tanks without sand beds tend to develop accumulations of nitrate over time. Yes, there are some detractors of DSBs on the popular message boards, and a few people are trying to go "retro" back into the bare-bottom "Early Berlin" style of the mid eighties. They tout the ease of being able to remove detritus from the tank, the "cleaner" look, etc. I'm a bit puzzled as to why people want to go back to a technique that really didn't work that well in the eighties...Personally, I think that the new bare bottom trend is just an excuse for running super-powerful pumps without worrying about blowing sand around! Aggressive protein skimming and good husbandry- mandatory for any successful system, are crucial in bare-bottomed tanks. I sincerely believe in my heart that a well-maintained tank with a decent sandbed can run for years and years without problems. Do get different opinions on this, of course. Good luck! Regards, Scott F> Abandoning an UGF in a newly set-up 90 gal marine tank and feeding triggers Hi gang,<Hi Ed, MikeD here> I think you guys are doing a wonderful job.<Thanks, we try> My question is I have a 90 gallon fish only that has been up and running for 1 month, it took 3 weeks to cycle,<Be careful. in that short a time even the tiniest glitch can cause it to re-cycle or go into a mini-cycle.> the first question is I put an UGF in before I saw your site, I have 2 300gph power heads running on the up tubes, is this ok or should I get rid of the UGF, I have 6 inch crushed coral covering the UGF, and is it ok to just pull the tubes and cover up the holes without removing the UGF.<This would be my suggestion. I've done it in the past with no problems. On an olde tank you might have sufficient accumulation beneath to warrant siphoning out the mulm, but here I suspect you'll be fine> Second I have 2 trigger and a coral beauty<2 triggers can be a bit much in a 90 as they grow, so consider yourself warned> that are carnivores, I have found that our local Wal-Mart store has in it's sea food section what is called sea food melody, the guy working there said it's just left over and it has squid, clam, crab, and some sort of fish, all raw and unprocessed, I gave ground some up in the food processor and the fish love it.<It makes an excellent food as long as you don't grind it too fine, where it can pollute the tank. Your triggers, for instance have very strong jaws and sharp teeth. I just cut it into small pieces with scissors and feed until they lose interest, then stop> Is it ok, should I add some vitamins?<You can> Last question is I was given some what used to be live rock which I bleached and washed and left out in the hot West Texas sun to dry and let the bleach dissipate, I put it in the tank with my 25 lbs of live rock, I was told it would become live again over time, is it ok to do this?<Yes, it WILL eventually become part of your LR as well> I was told it would be ok, well any way I read your site daily and enjoy it very much.<Thanks for your interest and support> Thanks Ed from West Texas.

UGF and High pH? - 04/18/2004 Nothing has been added; no rock, substrate, nothing.  I'm doing everything the same. Source water is 7.0 or greater, but has been that way, and ph has always stayed down, 6.4-6.8 or so.   <Accumulated organic debris under the filter plate will tend to drop pH.  Ah, is it at all possible that you were more thorough than usual on your most recent gravel vacuuming before the jump in pH?  And again, any large decor items that might create a "dead spot" under the filter plate, where you don't/can't vac under, and where there is no suction through due to the footprint of the item?> I tried SeaChem buffer to get ph down a little but it did not budge... <What product did you use, specifically?> That is when LFS said it was UGF set up for 10 yrs + , don't know what to do.... oh, and yes, I regularly vacuum <It is not my experience that an aged system using UGF will go *up* in pH, but the exact opposite - pH should drop due to decaying organics trapped beneath the filter plates.  Another thought, perhaps your test kit reagents are old/expired; try testing with another kit (new, a friend's, even the LFS, if necessary) to verify your readings - and keep in mind the dipstick-type tests can be grossly inaccurate.  I do hope we can help you figure this out.> Monica <Wishing you well,  -Sabrina>

- Undergravel Plates - HELP! I've been reading on a reef forum....I may have a problem! Many years ago I had just a fish only tank with and undergravel filter and an emperor filter.  A year or two later I pulled out the UGF tubes and just had the emperor going.  I never removed the filter plates. Now, many years later, I have a semi-reef tank.  I have 90 lbs HI/live rock, corals, inverts etc.  BUT...I still have the undergravel filter plates in! <No worries.> On the forum they said the crushed coral could reach a saturation point and cause major problems....HELP! <Don't know what 'they' are talking about... saturation point... sounds like mumbo-jumbo to me, voodoo economics and such. I say don't worry, you have what amounts to a simple plenum system going there.> Also, I just added stronger lighting a few days ago.  I have noticed every once in a while bubble coming out of the substrate??? <Unless the arrival of the bubble at the surface of the water is accompanied with a nasty Sulphur smell, I wouldn't be concerned.> Everything is healthy in the tank and the water is clear... is there anything to worry about? <I say no.> Thanks so much! Daryl <Cheers, J -- >

Undergravel filter  (9-9-03) Hello again, I really could use some direction.  About 4 months ago I transferred several small fish (2-3") I had in my 20 gal tank I also added a few inverts (3 shrimp, 2 brittle stars, 12 blue and red leg hermit crabs and a bubble tip).  My new tank is a 45 gal. It has an under gravel filter with around 3 inches of Florida crushed coral.  The aforementioned was all installed prior to finding you web site, weak timing I guess. There's also an Eheim canister filter and a Remora C skimmer with 2x24" compacts (130 watts total).   I at least had your advice with the skimmer purchase which is working fine.  I realize I should have gone with more lighting and I'm going to try to see if I can add an extra 30 watt florescent bulb but room is an issue with my AGA hood  All inhabitants are doing fine although my nitrates have been a bit difficult to control.  So I just purchased 22 lbs of LR, which is in the process of curing. I'd like to add a few "easy" corals and maybe a clam in the future. What I am asking is should I shut down the under gravel filter like I've been reading if so is there any special what I should do this, i.e. prior to adding the LR, and possibly add some live sand. Or should I keep the filtering status quo.   Essentially what would you do to get back on track?   <I would take out the undergravel since they are just a nutrient sink.  Also do this before you add LR as that will make life much easier.  I would stay away from any clams as you don't have nearly enough lighting.  You could try a few of the hardy soft corals like colt or leathers.  Just keep reading and learning and you will do fine.  Cody.> Chuck

Burying His Undergravel Filter... Hey guys you sold me, the Undergravel filter is history. <Well, the UGF is one of the most venerable tools of modern aquaristics! It has its place, even today. However, with more efficient filtration methodologies developed over the years, the UGF comes up a bit short...> Any thought on how this would work, I have an extra unused Eheim canister filter I was thinking of removing a portion of the current substrate placing it into a nylon bag and then into the Eheim with a filter pad.  Next I'd remove the remaining crushed coral and the filter plate.  Add the cured LR and LS then about a month later remove the crushed coral Eheim from the system. <A very good idea! That's pretty much what I would have recommended. I have seen other people simply leave the filter plate in place without problems, but for the majority of applications, removal is desirable.> Or should I save some extra work and just remove the substrate and plate while leaving the current (standard filled) Eheim and Remora  running? <If you can swing it, this would work, too. However, it would probably result in more "stuff" in the water for a while...> Thanks to all you guys your guidance is greatly appreciated.   Chuck <And thanks very much for your kind words, Chuck! Best of luck on your conversion! Regards, Scott F.>

-Undergravel filters: the saga continues- Hey guys, I am a little bit between plum frustrated and simply discouraged. I have a 35 gallon Hagen tank, one Aquaclear 200, one Aquaclear 150 and a 150 watt heater. I have literally months of planning and research behind me now (your site has been most valuable to me). <Excellent> Here is what I am aiming to do for my fish-only marine tank (two false Percula Clowns, one yellow tailed Damsel, Flame Angel and Maybe a yellow Tang. <The tanks already small volume along with it's lack of length should pretty much deter you from purchasing any surgeonfish. Even small, young tangs/surgeons require a 4' tank.> Pretty much stocking in this order). I plan on getting two AQUACLEAR POWERHEAD #201 and connect them to an U/G filter's updraft tubes, one on each of the two back corners of the 36 X 12 tank. The question for you is this, with all the controversy and differences of opinion I am getting on the use of the U/G filters, should I go this route or not? <I wouldn't, with all the info out there, I'm surprised that this is still even an option for marine tanks since there are so many better ways to go about it. Our preferred method of filtration is with live rock and live sand. It's a much better long term plan to keeping your tank happy and healthy. Check out Bob and Anthony's new book in the Natural Marine Aquarium  Series entitled Reef Invertebrates. There's a few chapters on the benefits of LR and LS and much more.>   If not. how would you recommend I set up the tank. I am pretty sure you are going to recommend a protein skimmer. <Muhahaha...> A Prizm hang on skimmer is in my plans as well. <That should work fine, although a better choice would be an AquaC remora>  but I am told and have found out that I won't need it right away and I should be careful of overskimming such a small tank. <You'd be hard pressed to overskim this tank with a remora, and there's no way in the world you could overskim with a Prizm.> would you agree with that? I am attaching a web address where the lay out of my tank has been pretty much accomplished with the exception of some slight differences, and the manager at a very well known local fish store has agreed that I should have no problem at all with what I plan to set up i.e. the use of U/G filter. http://www.equariumonline.com/fish_site/main.asp (look under The Set-ups: 36x12x16 and undergravel with 2 powerheads. I realize that this is long winded but I would just like to be sure of my direction before I start filling the tank with water and 25-30 pounds of live rock. I hope you can put my mind at ease, Thank you so much for you help in advance. <To sum up why I would suggest against using an undergravel filter in this setup in two words: detritus trap. Installing a 3"+ deep live sand bed would give you soooo many more benefits (i.e. natural food production, denitrification, excellent nitrification, etc). Check out http://www.wetwebmedia.com/livesand.htm for more info, and good luck! -Kevin> Cheers. <PS. in retrospect, this may seem overly biased.... and well... it is :) Live sand is a much better route than UGF. Do some forum searches on reefs.org and reefcentral.com to add to your information arsenal (sp?!)> Mike

-Undergravel filter part 2- Okay, I am taking a deep breathe. Thank you for your input you guys are so patient. <Hehe, comes with the territory> so this is the set up as I am seeing it. -35 gallon glass tank 36X12 -Aquaclear 200 filter -Aquaclear 150 filter -150 watt heater -Two AQUACLEAR POWERHEAD #201 -one hang on protein skimmer -3" Live sand substrate -25-30 LBS. of live rock -two hardy fish let cycle for about 5 weeks testing water frequently and regular water changes then add more fish down the road. Question: The two powerheads, any particular direction they should be aimed? I am thinking at 45 degree angle toward the center front of the tank as these two powerheads don't oscillate. <Orient them to eliminate any noticeable dead spots (keeping in mind that flow through and behind the rocks is important). Also make sure you have plenty of surface agitation> Anything overlooked? I am not usually this anal about things I just want to be sure that the little guy have the best chance of survival and not due to ignorance. I am sure you understand. <I do, but wish more people did... :(  -Kevin> Thanks again. Mike

- To Do Or Not To Do (Removing UGF from 17 y/o aquarium) - I have a 90 gal. fish only tank, been running 17 years now, no major problems.  <Great! I wish you future success!>  I have used crushed coral(3 inches)  with U G filter since day one. I use 1 canister filter, 1 Eheim wet dry filter, Remora skimmer, UV light and 4 power heads. I had a French Angle live 15 years with this set up. My question is, I would like to get rid of the UG filter but continue with the crushed coral (not sand). I know about the nitrate trap, but it seems under control.(10)  <Sounds good>  If I can do away with UG, (and should I) how deep should crushed coral be and what effect will this  have on system.  <The biggest impact will be when you tear it out. Over the years it has likely accumulated a whole ton of detritus and will make quite a mess when it gets pulled out. Since it's been there soooo long, you may want to just disconnect the riser tubes and powerheads. I don't see any advantage of removing it and keeping with crushed coral.>  Also I would like to add 1 piece LR, (for looks only and seed for coralline algae.) Do you think this will improve system or have no effect what so ever.  Thanks, Wayne <Live rock is always well received. It will benefit the fish by adding new and tasty types of algae and critters to their diet. I'd suggest it. Good luck! -Kevin>

- Removing UGF from 17 y/o aquarium, take 2 - Thanks for your quick response, My main question however is how deep should crushed coral be if I do remove UG filter as I am not depending on LR for filtration as it will only be 4 or 5 pounds at best.  <Well, you do have that wet/dry, but I'd suggest more cured live rock. I'd leave only about 1/2" of crushed coral for ease in maintenance.> Over the years I have torn apart and cleaned under the  UG filter, so detritus build up not a big factor. Please let me know what best depth of CC should be.  Thanks Again,  Wayne  <Check out Bob and Anthony's new book Reef Invertebrates for the spectacular chapter on just this subject. But again, I would suggest more live rock if the wet/dry isn't or is just barely suitable. Good luck! -Kevin>

- Finding Undergravel Filters - Hello, I'm looking for an undergravel filter system called the "BIO-GRADE Plus " from Aqualogy. The company is located in Newark New Jersey. <I've never heard of them, but then again, I live under a rock in some respects... was not able to find via Internet searches.> My tank size is a 55 gal., 36" wide, 15" deep. It's hard to find the right undergravel size to fit these dimensions. <Any chance I can convince you to skip using the undergravel filter. They work, but there've been enough significant advances in the aquarium trade that you have other, more efficient options. In addition, they really do end up being detritus traps and not really in your best interest.> I'm using one now that is 30" wide and 12" deep.  I live in Palm Springs and would like to find a place in this area to purchase it. I appreciate your time. Thank you. Ron <Cheers, J -- >

Undergravel Filtration/Marine Customer has  fish only marine tank, with an undergravel filter & 2 power heads - hang on back canister.   >>This kind of setup can work just fine (yep! I said it!). I had to break down tank and move due to repairs to home.  Will reset up days later.  Well, to my surprise i found polyfill covering the undergravel plate like you would use to stuff pillows.   >>Oh MY!  What a surprise, Tanya/Rocky.  I hope you didn't get palpitations. He does not want to spend money to up grade system.  Can i cover plate with window screening?   >>Absolutely you can, as long as sand isn't the substrate (it'll clog the screen).  Just also be sure to use no metallic screening, either, you'll be golden. Can hardly wait for new book.  Thanks as always your mutual friend in fish.  ROCKY >>Neither can we!  You're most welcome, especially as a mutual friend.  Marina

Removing under gravel filter? Hey There. First off I just wanted to say that I have found a lot of very useful info on this site. You guys have actually saved me a lot of time and money. I currently have a 55g FO marine tank. It has been completely cycled for about a month now. My original equipment is an Aqua clear 500, UGF w/ two power heads rated at a total of 445 gph, and a Bak pak 2 skimmer and bio filter rated up to 60 gal. Now I am ready to pull the UGF after all of the negative info I have read about them. About two weeks ago I bought a Fluval 404 and filled every chamber with bio media except for one that has carbon. Yesterday I pulled The smallest of the two power heads running the UGF and finally My question is, Am I jumping the gun? Should  I let the Fluval seed a bit longer, Or am good to go. Also, When can I just completely tear out the UGF all together? My livestock includes 2 inch Coral Beauty, 2 inch Yellow tang, 1 inch blue damsel, .5 inch damsel.   Thank you Jason Auringer Austin, TX <Hey Jason, I would run the Fluval for another week or two then yank the UG.  It is probably ready to go, but better safe than sorry.  Best Regards, Gage>

DSB / Old UGF Plate Hello to all: Due to potential of 'yuckiness' building up, is it a bad idea to use a filter plate underneath a DSB of 6 inches?  The plan is to use +/- 100 lbs of LR, Red Sea Berlin H.O skimmer, Fluval 404 canister, and various powerheads for circulation within a 75 gallon reef tank.  I also have 440 watts of VHO lighting for my eventual guests.  I do plan on keeping several small fish such as Blennies, gobies, and damselfish.  Thank you in advance. A Russell <Yes, under gravel plates are yucky, you do not want to use one underneath your DSB.  Check out the link below for more info -Gage http://www.wetwebmedia.com/deepsandbeds.htm  >

Unhappy new addition?? Hi there again, guys! I have a zillion more questions for you, but I'll limit this session to just two. I have a 20 gallon saltwater, UGF, etc. I purchased a tank raised Percula clown yesterday, acclimated him, and he seemed okay. My yellow-tail blue damsel started attacking him and wouldn't leave him alone. He even tried to bite! He was smacking him in his face with it's tail and had him cornered and wouldn't let up. <This is not unusual behavior for damsels. They are inherently territorial and aggressive.> Needless to say that the damsel is now gone, but the clown (Waddles) is still hiding and won't eat. I had to really move around some rock to get that little @#*&@ out. Is he still unbelievable stressed or should he have a companion (there were 4 in his tank at the LFS)? <I would bet on stress, damage, even just plain old fear.> My Domino damsel doesn't bother him. <No yet!> Any suggestions? <I always try to plan out every fish I put in a tank before I put any in. Come up with a game plan and you will have fewer problems like this in the future.> Now on to question number 2. My tank has been up and running for over 6 weeks and my nitrates are still hovering around 25 ppm (according to how the test reads). The guy at the LFS suggested that I do a 20% water change since in his opinion it seems my tank is "stuck" (ammonia zero, salinity is normal). The nitrates have been at this level for about 2-1/2 weeks, maybe a little longer. Any suggestions on that as well? <I am a bit confused. You will always have nitrates with an undergravel filter. You do not have a Deep Sand Bed to perform denitrification. Perhaps you should invest in Mike Paletta's "The New Marine Aquarium." It is an excellent first book. Very easy to read and pretty short, too.> Thanks again, Maureen <You are welcome. -Steven Pro>

Dastardly Dascyllus Behavior Steven, You can disregard the question on the clown (Waddles). As of this morning, he is eating and swimming all over the tank. Hope his days of being stress-free are over. <I am glad to hear it.> As for my Domino, so far so good and I'm keeping my fingers crossed. <You can hope, but this fish is going to be a fish. No changing its behavior. Domino's are categorically one of the meanest fish out there.> I know he'll eventually have to go, as I wish to purchase some Cardinalfish in the future. <Agreed> As for my second question, I don't think you answered it. <Perhaps I was not clear enough.> My nitrates (been at this same level for 2-1/2 weeks or so) seem to be "stuck" at 25 mg/L (according to the test) and the guy at the LFS suggested I make a 20% water change since in his opinion, the tank seems to be "stuck" at the end of it's cycle. <You LFS guy is incorrect about the cycle. You said you tank is run with an undergravel filter. If so, you will always have nitrates. You do not have a sand bed and are therefore unable to culture denitrifying bacteria. You will always have nitrates that you will have to continually try to dilute with water changes.> Been up and running for 6 weeks, ammonia zero, salinity is normal. What is your advice on this? Should I make a water change? <Yes, but do not think that eventually you will not have a need for them. Even with a DSB and complete denitrification there is always a need for water changes.> Thanks, Maureen <You are welcome. If I was not clear enough or you need further explanation, feel free to email again. -Steven Pro>

Marine Set-Up (one question at a time) Respected sir, Well sir, after cycling, can I take out undergravel filter? <Monty, please, please, please do some reading, for both mine and your sake. You have sent us an email everyday single day for almost two weeks now. They are the most basic of questions and if I do not cut you off at some point you will never learn anything on your own. The undergravel filter and gravel provide a means and a surface for needed, beneficial bacteria to grow. If you remove the undergravel, what will happen to that bacteria and the ammonia and nitrite levels in your tank? When you discover the answer to the above question, you will be able to decide if you can remove the undergravel filter or not and what could use to take its place.> Also I want to know that what other rocks can I use? <Take a look here http://www.wetwebmedia.com/aquascaping.htm> In my marine tank, the little part of marine salt is not dissolved. It is sat down over coral sand. My specific gravity is 1.011 right now. <That is more like brackish conditions.> I don't have any marine salt right now. I had ordered it. It will come in about a week. <At that time, you should increase the specific gravity to 1.020-1.025. -Steven Pro>

Starting Over It's me again. Thanks Scott for your reply. <Glad to help!> I am now thinking of re-starting my system (the only way). I read that UGF leads to CO2 poisoning, should I continue using it, does adding powerheads for circulation helps? <Well, undergravel filters have their pros and cons, and are still used with success in a variety of systems. Really depends on what you're trying to achieve.> If not, what type of filtration is recommended? Just to remind you, mine is a 25g tank and I have a Sander piccolo skimmer (works fine).   <Wow- so many possibilities here. Keep the protein skimmer cranking away, removing lots of dark skimmate weekly, and you can try many different methods. I tend to favor more "natural" methods, such as deep sand beds, live rock, sumps, etc. You can read all about these techniques and systems on the wetwebmedia.com site. Choose one that works best for you, have fun putting it all together, and enjoy!  Let us know if you have further questions! Scott F.>

Undergravel Filters/filtration, marine Respected sir, Today, I see in your biofilter faq section in which you have to said to one lady that putting an undergravel filter is harmful. <Harmful is probably too strong a word. Undergravel filters are inherently more work, than other alternatives. Once you get and read those books I mentioned previously, you will see the merits and minuses of each methodology.> Well sir, I had also set up with U.G. FILTER, so please help me. Also you are most welcome to come my house any day you can come. MONTY <Thank you for the kind offer. -Steven Pro>

Gravel Filtration Do you recommend gravel filtration? <Method of filtration depends on many factors, freshwater, saltwater, fish, reef, etc. Please surf over to http://www.wetwebmedia.com/ and choose your weapon from the headings...marine or freshwater, and then the sub headings for filtration. It is vital to factor-in the type, habit, feeding, waste production and adult size of the inhabitants you are interested in, and what is required to provide them with whatever it takes to thrive in captivity. The web site will provide you with all the information needed. Enjoy! Craig>

Converting from Undergravel to Berlin I have an established 85 gallon tank with 6 fish, 2 corals, 2 anemones, some live rock, and a big algae problem. After having tried all the usual fixes, I would like to try taking out the undergravel filter and replacing the crushed coral with live sand. <Ok> Are you aware of any articles on the steps to follow in doing this? <There is no definitive article on this as all tanks are different. You mentioned some liverock. The amount of liverock you have may lessen your tank's reliance on the biological filtration of your UG. You should have about 100 pounds of liverock to effectively filter this tank.> What do I do with the animals and rock? Can I do it all in one day, or do I have to do 1/2, and let it rest? <I would suggest doing this all in one day, with some preparation beforehand. Assuming your tanks needs the undergravel filter, I would add several large sponge filters (they are cheap and readily available) or other biological filtration to the tank. Let these work and get seeded for one month. At that time, you should be able to safely removed the crushed coral and undergravel filter.> I'm concerned that if I remove the undergravel filter and the crushed coral and vacuum out all the debris, I'll lose all my bacteria and the aquarium will cycle and spike before the new bacteria becomes established in the live sand. <Agreed, that is why in my recommendation above you will supplant the undergravel's capacity with sponge filters.> I'm concerned about the conversion upsetting the water chemistry and harming the fish before the system stabilizes. Is this a real concern and if so, is there anyway to deal with it? <It is a real concern, see above, and please use the google search engine on www.WetWebMedia.com for additional enlighten.> This aquarium is the only place I have to keep my fish, etc. Thanks in advance for your advice on this problem. <Good luck! -Steven Pro>

Re: converting from undergravel to Berlin Sorry to bother you but I'm not sure I understand your response to my question. I asked about the steps for replacing an undergravel filter with live sand. Your reply talks about sponge filters but did not mention live sand. Was that intentional? <No, do go back and look for all the arrows (<...>) for additional information. The basic point I was trying to make was that you cannot just remove all the crushed coral and undergravel plates all at once because your tank and its bioload are relying on the nitrification capacity of your undergravel. If you yank it out without something else there to pick up the slack (the sponge filters) you are going to have a tremendous ammonia spike and probably wipe out your tank. That is why I suggested using the sponge filters as a temporary solution. Get them seeded so you can remove the UG and crushed coral and add live sand. Then later, as the sand becomes fully seeded and you have the appropriate amount of liverock, you can slowly take out the sponge filters, one at a time over a month or two.> Thanks, Jack <You are welcome. -Steven Pro>

Undergravel filter Hey Bob & crew, Hope to see you at Aquatic Warehouse sometime soon... <Was just there two days back... chatting w/ Pat Hurley with friends visiting from Michigan> I started my tank in Sept 2001 with a reverse flow under gravel filter using two powerheads (I also used a canister filter). I have converted to a Berlin sump system and want to remove the powerheads for the UG. I removed one powerhead 2 weeks ago and am wondering how long I should wait to remove the other one.  <Now is soon enough> I am concerned about shocking the system with whatever is happening below the gravel. Thanks for sharing your extensive knowledge with all of us! Michael <Thank you for sharing. Bob Fenner>

Filter System for Reef Tank II Hi Steven, Thank for you comment. I would like to know the pro and con of this system I mentioned below. I had seen many articles on undergravel filter and their con are -Detritus trap, ( wastes collect in the gravel requiring frequent cleaning)  -Carbon dioxide poisoning, (builds up near the bottom)  -Low bioload handling  -Prone to NTS, (new tank syndrome)  -Non-reef compatible, (fish only)  -Unstable pH requiring constant buffering, (acids and Co-2 build up causing a depression of pH)  -Live rock not recommended with this filter, (not enough O-2 again)  -Frequent water changes to export accumulated nitrates  and phenol oils, etc.  Does this apply to the filter driven by power head. Will debris trap on the substrate? <Yes> I need your help. Because I am setting up a 4 x 2 1/2 x 2 1/2 reef tank and I do not know if there is any method that can filter out debris on the substrate? <Far better to use a fine grade of sand and vigorous circulation to keep detritus in suspension to allow its removal via skimming.> At present my 70 gal tank only use the dry/wet method and I need to siphon out the debris using another power head. Is there other method that I can filter out the debris easier. <Far too much to communicate in a short email. Please look through the various writings on WWM. To start, my preference for reef tanks is purified water, DSB, liverock, protein skimmer, vigorous circulation, and appropriate lighting.> Thanks again, Danny <You are welcome. -Steven Pro>

Filter System for Reef Tank Hi Bob, <Steven Pro this morning.> I am setting up a new reef tank and I intended to set up a filter system seem like undergravel filter system but there is no filter sponge below and does not use air bubble to work. It had a powerhead underneath the substrate and suck up water to a external filter. Please see my diagram attach. I wonder if it would work? Can you give your comment on this? <Yes, it would work. It is much like the modern UG filters, but this type of system is not really the best for a reef aquarium. Take a look here for additional information and follow the other links at the top of the page, http://www.wetwebmedia.com/reefsysi.htm> Thanks a lot.. Danny <You are welcome. -Steven Pro>

Questions about Reverse-Flow Undergravel <<JasonC here, filling in while Bob is away diving.>> Hi. I am in the planning stages of setting up my first marine tank. Forgive me if this is covered elsewhere on the site, and please point me to it if it is, but is there a definitive answer as to whether reverse-flow undergravel filters are preferable to standard flow? <<Without looking, I will guess you might find Bob saying that in a FAQ, but you'd have to do the Google search to find it... hang on... found it: http://www.wetwebmedia.com/marsubstr.htm - point #7>>  Does it depend on the substrate and/or the livestock? <<you mean if one would employ such a system, I would say for a certainty, yes.>> For example, if I want to set up a plenum with live sand and live rock, and I plan on having an anemone and other invertebrates (but not coral just yet) what's the best way to go? <<if you want a plenum, and live sand - no undergravel filter for you - reverse flow or not. One or the other in the main tank. Nothing is stopping you from putting a refugium outboard of the main tank.>> I also plan to supplement the UG with a hang-on power filter. <<Many, may choices - start with that link.>> It's going to be a 40-60 gallon set-up. Thanks very much, and thanks for this invaluable site. Tim L. <<You are welcome. Bob will be reading this and will appreciate your kind remarks. Cheers, J -- >>

Undergravel filter tube/power head Hi Mr. Fenner! I hope this finds you healthy and happy today. <Thank you my friend. I wish the same for you, all days.> Got your book the Conscientious Marine Aquarist, it is a fantastic book! Anyway, I would like your advice on a small problem that I have. A few days ago I was doing routine maintenance on my salt water tank and one of my power heads broke, so I ordered a new one and put it on the undergravel filter tube where my old one was only to find it stuck up above my aquarium and I needed to cut the tube to make the new power head fit, well after trying to pull the tube out, I found that it was stubborn and did not want to come out, so I took a knife and cut the tube while it was in place...well I got the new power head on and now it is sucking crushed coral up through the tube. My questions are this...should I try taking this tube out again to take care of gravel problem or cap the tube off and leave it in there and just mount the power head elsewhere. My tank is 45 gal. and I have a power head on the other side. Will it create a problem under the undergravel filter with only one power head to pull water from under it? <Mmm, there are some undergravel units that are "one plate" for such size systems... others that are in two separate pieces... if yours is one piece just running it with one powerhead, capping the other riser input should be fine... and is very likely what I would opt to do... there will be enough flow by way of the one powerhead here. Do fashion an intake skimmer about the new powerhead intake that will prevent sucking up your livestock...  Thank you in advance for any help you may give. Have a great day! Jenny <You as well. Be chatting, Bob Fenner>

Undergravel (filter for marine system...) I have been in the hobby for 12 or so years and have went through a lot of money fish corals and so on.  I feel it was worth it though. I have learned the hard way in most instances. Well, to my ?, I have 44 pentagon tank that I have made into a reef tank. I built a canopy for my lighting which consist of 2 24in VHO one of course blue the other white and like wise with the 2 36watt pc. My dilemma is whether or not to take the UGF out or not? It has 2inches of live sand covering it large enough not to fall through the UG plate. It also 50 pounds of live rock in it which came from a 135 gal tank where I have a 3 foot zebra eel. To pick up the problems of the UG I have a overflow box which leads to three layers of batting and about 4 gallons of bioballs, which will come out soon. There is as well model 200 top fathom skimmer. Fish consist of a juvenile asfur that I will raise there until he out grows the tank. I just hate to tear the tank apart for the UGF to be removed.  Could this be use as a plenum if I took the power heads of it? <Yes... this is exactly what I would do... turn off, remove the mechanism... air lift, powerheads... that move water through the gravel, filter... leave otherwise as is> The corals are as follows a brain a torch a hammer, xenia, bubble and mushrooms and that is it to this point. Any suggestions other than get the UGF out of there? <Mmm, not really... at this point at least. When you get the new, larger system for the Asfur, perhaps the eel... and non-fish livestock, you can disassemble and remove the plate/s. Bob Fenner>

Re: Filtration Dear Robert, Is there such a thing as over-filtering a system?  <Yes... though rare... much more common is "mis-filtering", under filtration> I use an underground and a conventional air filter that have maximum capabilities that are a bit more than the size of my tank. Will this hurt the fish? Thanx. <No my friend. Bob Fenner> -James Kim

Bioball removal, all at once, mistake? Mr. Fenner, I think I messed up big time. I am planning on building a refugium and took out the bio ball in my tank.  In one afternoon, all of them. Now my bubble coral is turning dark and sucking up. Should I quick replace some of the bio balls. I did some test Ammo & Nitrite 0 Nitrate 30ppm. <I might put half of them back... but what will you do re the nitrates? Please read here: http://wetwebmedia.com/no3probfaqs.htm> When I took out the bio balls I did do a water change. The coral has always kind of shrank back when I do that but this is frightening. Is it stress?  <In a word, yes> My Xenia and mushrooms look good as do my fish. I am very concerned. Could you help? I'm afraid I have hurt my tank badly. Don <Need to know more about your system, components, other livestock, maintenance, history... Bob Fenner>

Re: Bioball removal, all at once, mistake? Mr. Fenner, Thank you so much for the fast reply about my bioballs take out. I have read about refugiums and the good they can do for a tank. I thought that it would be a good idea for mine. I wanted to build it into my wet/dry filter. <Good idea> Hence why I took the bioballs out. I wanted to put in some live sand in the next few days to a week, then rock and macroalgae. That would care for my nitrates if I am correct. <Yes, likely so> I asked my LFS (just discovered your site and all of the info on refugium this afternoon) if it would be okay for my tank in that time to let the system run like a Berlin system. Thy said that my tank was stable enough for such a plan. I had no idea that the ball being taken out had to go more slowly. <Sometimes not... if a system is well-aged, has a good deal of life "elsewhere" (like in the main/display tank) plastic wet-dry biomedia can often be pulled all at once. But doing this in increments is safer of course> My tank has been running for over a year now. Ammonia and Nitrite 0, Nitrates 30ppm, dkh10, Ca 425. My tank is a 55 gallon hex. I have a hippo tang, a mated pair of bangtail cardinals and a lawnmower blenny's?) <blenny> A bubble coral, pulsing xenia, polyps and a hitchhiker mushroom. 75lbs LR and 70lbs LS. AquaC skimmer, 380 watt PC lighting. I have had good luck for a long while. I do a weekly water change with aged circulated water. <All sounds conditions, gear-wise, but the accumulated nitrates> For about 4 weeks now when I add the new water my bubble coral does rather freak out. By that I mean she shrinks up and sends her stingers out slightly. Today when I took the balls out and did my water change it turned gray in areas and did not look too well. I am wondering if there is something in the water or my taking the balls out did a number on her. Like I said everything else looks well. <Better to change water in smaller increments perhaps. Do you use just tapwater in making your synthetic (or are you using natural water?), you might want to look into treating the tapwater first> I have read over your web site on refugium and though I understand more I wonder now if I should press ahead with the refugium or go back to the bioballs. Does this added info help you guide me better. <Yes. I would go forward with just the refugium: lighting, macro-algae there... this will greatly improve the system overall> I hope so. I am feeling like a cruel tank master right now. This is a hard hobby when one is give poor advice and needs to make up for it. I hope to hear from you again soon. Don <Be chatting, and studying my friend. Bob Fenner>

Gunk! Hi Bob, I have not talked to you in a while. Your help to me in the past has always helped so again I seek your knowledge. About 6 mo. ago I set up a 55 Ga.. I have been keeping fish for most of my life. (32yrs) I have kept almost everything. (yeah right!) I got back into salt after two years of being away. (new marriage etc..) Could not stay away for long. I have had my 55ga. FOWLR (Buttons only on 1 rock. 4x's more than when new.) setup for about 6 months. Twin tube NO Flour. (1 Triton + 1 Power Glow) to keep 50lbs of live rock going. I have 6 sm. fish and a few crustiest (Brittle Star, hermits, Sally Light Foot and a Coral Banded Prawn). I change between 10 + 15 Ga. of water every 10 days. I siphon most of the exposed substrate each time I do a water change. <All sounds much like myself...> In the past as well as now, after about 6 mo. I take out the live rock and total purge the entire substrate. Replace everything and move on. Why? Because after that time frame, my substrate always keeps coating itself with Cyano and red slime algae. The live rock suffers too. <Yes... an easy approach... more circulation, lighting... would extend this time frame> When I do this I get between 15 and 20 gallons of darn near black waste water! Nasty! So much crud collects itself under the homemade reef wall that it amazes even a cleanliness stickler like me. So many times I hear reefer's complaint of algae in a long time setups. It makes me wonder how much sludge is under their reef? <Or why natural environments don't seem to accumulate such> I plan on getting back into reef keeping this year and I will continue to do what I have always done in the past. I take the time to break down the tank (super carefully) and clean that nasty substrate. How can a reef tank keep going after years of not doing so?  <A few ways... use of more purposeful denitrification sources... accumulators of nitrates et al. metabolites> My goodness! The D.O.C.'s, phosphates and all the rest of the nasties thrive in this type of environment. Should I do this on my new reef or not? <Let's continue our discussion here till your options are clear... I encourage you to read through the site (www.WetWebMedia.com) as it has grown quite a bit since our last conversations... and consider a refugium/sump and more...> Am I smart or just plain stupid? <Perhaps both, or neither. Who knows but yourself?> It is just hard to believe after seeing so much super nasty crud that collects after 6 mo., that a reef could really thrive in that type of polluted environment. Hmmmmm. Zimmy <There are as many opportunities as there are trials my friend. Seek yours. Bob Fenner>

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