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FAQs on Denitrators, Denitrification

Related FAQs: Sulfur-based, NNR (Natural Nitrate Reduction, Anaerobic Bacteria), Biological Filtration, Deep Sand BedsFluidized Beds, Ammonia, Nitrites, Nitrates, Phosphates, Wet-Dry Filters, Bio-Balls

Related Articles: BioFiltration, Nutrient Control and Export

MY TANK... ongoing, re reef set-up, Siporax use     2/10/12
The story so far sps dominant reef
This is what I have ordered.
 6'x2'x2' DT rimless euro-braced 70g sump
DaStaCo calcium reactor
Deltec 30/70s ext skimmer +self-cleaning head
4x Ai Sol 40/70 LED
2x Deltec E-flow 10 [32mm outlet]
4x Vortech MP40s
2x Return bulkheads 32mm
4x Overflow to sump 40mm
1x Fail safe  overflow to drain
RD/DI unit SpectraPure 90
LiterMeter set up as Scott at SpectraPure advises for auto top off and water exchange.
Live Rock
This is what I am undecided about: Siporax  in tower or canister bio-filter at high rate ?
<Not at a "high rate"... Likely there is no further benefit to be gotten by having more than 10-20 volumes of flow through this medium per hour... in fact, less is better in terms of denitrification>
 how high for aerobic activity and combined  with very slow flow 1 or 2 litres per hour passive bypass for anaerobes
<Oh! You're ahead of me as usual...>
DSB floor o DT
DSB the entire sump
<More the merrier>
Remote DSB
<Better for maintenance>
<A real plus>
Are you in general in favour of multiple filtration methods  and sometimes more than one of a particular type e.g. DSB and Siporax [when set up as low flow]
<Oh yes>
re: MY TANK, Siporax ap.     2/11/12

Dr. Bodo Schnell of Sera GmBh who manufacture Siporax states:
"The setup is pretty simple: The first step is mechanical filtration, e.g. sera biopur (clay tubes) or sera biofibres. The amount depends on the waste amount, practical values range from 0.5 liters - 1 liter. The main step is biological filtration with sera Siporax, and in this case I recommend about 4 liters plus a relatively slow flow rate (200 - 400 liters per hour).
After a few weeks (activation period) this will take nitrate values down considerably.
There is, however, another way: A separate slow flux filter in addition to the normal biofilter. This filter (a passive bypass system is OK) should then hold 2 liters sera Siporax, with a water flow rate of only 1 - 2 liters (no typing error!) per hour. This setup will produce virtually nitrate-free water."
There you have it. So its similar in function to the deeper layer of DSB..
The LFS  suggests using a tower rather than canisters and as the tank is not yet built that would be possible. None the wiser? Me neither
<Have added the quotation marks above... Yes to more Siporax (or other media for the purposes... aerobic and anaerobic digestion of nitrogenous et al. metabolites... And yes to slower flow rates, confining the media to a reaction chamber or not... but, as I've mentioned before, there is a need for alkaline reserve (carbonate, bicarbonate principally) and alkaline earth materials (principally Ca and Mg), and other rate-limiting materials (celebratedly Carbon)... to make all this work efficiently. Hence the suggestion of a fine DSBed of suitable material alone or in addition>
My thinking on it was that a Siporax system like this is accessible, simple to remove, and easy to maintain.  The product was born and died and has now been revived,  so always looking for lost causes I would give it a try if I could set it up right.
<I gather you're a "high tech" sort of guy; subject/susceptible to the influences of others to degrees, products that "flash"... I urge you to consider a more "biology", less technology approach, approaches... there are "many roads to Rome", but some cost a good deal more w/o granting a nice view, transit enroute. B>

Re Powerheads 10/6/09
Guess 2  #3's are better than?
<Better than what, or did you mean better then.  The Koralia 3 would be my choice for a tank with your dimensions.  James (Salty Dog)>
Re: POWERHEADS 12/16/11

any info on aquaripure.. does it work in saltwater tank?
<I have no experience or knowledge with that product.  Best to ask this on a forum, get users comments.  James (Salty Dog)>
Re: POWERHEADS 12/17/11... actually an alcohol-fed Denitrator brand    12/17/11

It's a filter that removes nitrates(injecting 7ml of vodka) running water through tube removing oxygen. Made by Aquaripure.
<Ah, a carbon doser.  May want to check out Tropic Marin's new product called Marine Actif.  It accomplishes the same thing but with no filter/reactor to fiddle with.  I am currently trying this product and it looks very promising.  My water has gone to the next level of clarity while nitrates are slowly decreasing.  James (Salty Dog)>

Re POWERHEADS 12/18/11 NO3 reduction/ants

please keep me posted on this doser
<Is not a doser, an additive.  I will send Bob any further input I may have on this product for posting in our Daily FAQs. <<None>>
This likely will not occur for a couple of months.  Do inquire at that time as we do not store/save queriors email addys.
James (Salty Dog)>

Nitrate Reactor producing ammonia  -- 11/08/11
Hi, hoping you can help.
<I as well>
I have an Aqua Medic NR1000 which was working fine until I had to take it out of action recently due to a faulty dosing pump, then a leak. The reactor was out of action for about 2 weeks.
I fixed it last week and set it running again, I got the usual rotten eggs smell but was not too concerned as this had happened before when I had it out of action for about 2 weeks, and it normally cleared after a couple of hours without any problem.
<Hopefully this H2S water was NOT circulating through your system>
I put the outlet into my tank and waited for the smell to clear (as before).
The lights were off so most of my fish were still in their hiding places.
I then noticed that my fuzzy dwarf was not looking to clever.
<Not too...>
I removed the reactor outlet from the tank and let the output flow into a bucket (the inlet was still being fed from the tank) and run the reactor constantly for 2 days, continually testing the water in the bucket.
I ended losing my Fuzzy Dwarf, Flame Angel and 3 Dispar Anthias (really gutted for them and me, but realise it was my own stupid fault)
The readings from the bucket are PH 8.0, Ammonia 0.5, Nitrate 0, Nitrite 0 The readings from the tanks are now PH 8.2, Ammonia 0, Nitrate 0, Nitrite 0 I want to start using the NR1000 again and have spoken to Aqua Medic about the ammonia, they have suggested that I clean out the reactor and start again.
<This is what I would do>
I will if I have to but this takes about 2 weeks to cycle which is really difficult and worrying when I have water being pumped out of my tank whilst I am at work (day) or sleeping (night). I don't have an auto top-up.
I am using Deniballs (which are fed with Denimar powder until ready) and Bactoballs.
My question is, do I really need to clean out the reactor and start again, or can I use something like AmmoLock or Amquel + to make the ammonia safe, or will there be some sort of reaction with the bacteria in the reactor.
<I would clean it out and start anew>
Also, I understand these treatments only make the ammonia safe,
<Only the ammonia present at the time of treating>
and it will still be read on a testing kit. How long will this continue for as I will have no way of knowing whether the reading I am getting is safe.
Sorry for the long post, any help would be gratefully received
<Welcome. Bob Fenner>
Re: Nitrate Reactor producing ammonia  -- 11/09/11

Bob, thanks for your help, I will start again.
<This is best Ger... IS what I would do. Cheers, BobF>
Re: Nitrate Reactor producing ammonia 11/14/11

Sorry Bob, can't resist tapping into you knowledge. The nitrate reactor is now up and running again with 0 nitrates, ammonia and nitrate being recorded from the outlet. It does however strip out the Ph.
<Yes; reductive events, reaction series>
I have placed the outlet into the skimmer compartment which buffers it a bit (between 7.8 and 8.0) Please can you advise what you would recommend to buffer the Ph back to normal levels.
<I wouldn't worry re... in time (a few days to weeks), most all the "easily reduced NO3" will be gone and the pH shouldn't be so drastically affected.
I'd count on your "other, present mechanisms" for buffering to rectify this in other words>
Thanks for all your help.
Kind regards
<And you, BobF>
Re: Nitrate Reactor producing ammonia 11/14/11

Thanks Bob, your help is really appreciated, Gerry
<Certainly welcome. B>

Sick valentini puffer    7/26/11
When I got up 3 days ago no fish was <were> swimming (I had 6 fish). Two angels have died all the rest was laying on the sand heavily breathing.
<Yikes... summat environmental>
The problem was lack of flow through the nitrate reactor for a few days resulting in rotting. I don't know how and why flow suddenly restored itself and pumped ammonia to the tank overnight.
Anyway, I've disconnected nitrate filter, changed media in canister filter, done two water changes, added ammonia binding chemicals and managed to improve water quality to the level which wouldn't harm healthy fish.
Three fish (snowflake eel, dogface, filefish) ,although still looking depressed , started to swim.
Except valentini puffer. He can move if he chooses to but in an uncoordinated fashion. For the last two days he has been holding upright position (on his tail) supported on the rock.
(What's the reason for this?, why is he not resting on his stomach like for the first day?)
<Poisoning/ammonia... likely will be fine in a week or so>
Breathing seems to be very fast and shallow.
I am concerned as he has no appetite so will be getting weaker.
Is there something else I can do?
<Patience; keep offering favored food daily>
Thank you for your help.
<Welcome. Bob Fenner>

Bio Pellets/Nitrate Reduction 12/8/10
<Hello Mike>
I was wondering what your thoughts are on the bio pellet craze. One in particular, Warner Marine Ecobak.
<The pellets are actually a dry form of vodka dosing without the vodka as a carbon source which means more vodka for me. I tell my wife it's called whiskey dosing so that way when the Jack gets too low,
I tell her the nitrates went through the roof last night. <<Oh, James!>>
I've heard good reports about these products but you need to follow instructions carefully. Overdosing these products can cause side effects such as rapid pH/dKH drops.>
Thanks much
<You're welcome. James (Salty Dog)>

Live Rock Substitute/Denitrification 3/27/10
<Hello Brent>
I have a question.
I have a 150 gallon aquarium [72x24x20] It is about 1/2 full of live rock.
I have a large trigger and a large king angel as well as a larger tang. The problem is they need larger holes and more swimming room. I was thinking of selling off some of the rock and getting larger pieces and using less rock. But I use the live rock for filtration. Is there any thing I could use as a substitute for the live rock that I will get rid of. I seen an ad for Seachem's matrix bio media and it claims to do the same as live rock [nitrifying and denitrifying bacterias] I was wondering if any of you guys have had any experience with this product or any other ideas for a live rock substitute
<I have not personally used this product, but will work well for denitrification in a sump tray or canister type filter where water is flowing through the product.
James (Salty Dog)>

Denitrators And Nitrite 8/27/09
<James with you today.>
I am in the process of setting up a coil/sulfur denitrator and am having a slight problem. Even at a slow drip of 1 drop per 3 seconds, I get almost 1ppm of nitrite. Is it safe to assume that the anaerobic colony is insufficient and only stripping off one of the two oxygen molecules from the nitrate? If so, would it be okay to allow the system to go to a complete stop allowing the reaction to go completely to the right. I know hydrogen sulfide may form, but the bacteria colony would increase, wouldn't it?
<No, once you smell hydrogen sulphide, anaerobic conditions have been reached and the reactor will not work properly as the denitrator operates under anoxic conditions.>
Once I smell the rotten eggs, I could start introducing fresh nitrates and expose the effluent to my Sander Ozonizer to oxidize the hydrogen sulfide.
Another alternative would be to run the denitrator on an empty QT and feed the colony some skimmate. Any golden nuggets of wisdom you could throw my way would be greatly appreciated.
<It will take some time for anoxic conditions to be established within the denitrator so do be patient. It is possible to speed up this process by the addition of a carbon source to the water. This carbon source will be processed by bacteria with3in the unit, using oxygen up and generating the low oxygen levels needed for proper operation. This can be done by adding about 25 milliliters of vodka (please do not use Absolut Vodka, is a waste of good vodka) or a sugar solution to the denitrator column.
Let the circulation pump run a day or so making sure no new water enters the column. This process should lower the ORP to a usable level in that time frame.
Then, start with a very low flow rate and check daily for any hint of hydrogen sulphide.
If it is detected, the denitrator will require more oxygen and a small increase in flow rate will be needed. This is the "fine tuning" period, and may take quite some time to tune in properly. If, after 4 to 5 weeks of operation, and no nitrate reduction occurs, you will need to reduce the flow rate a very small amount, and this may have to be repeated if after 2 to 3 weeks, no nitrate reduction is noted. This is the negative side of sulphur nitrate reactors, time consuming to properly set up and is the main reason I have never incorporated one in my system. Once the sulphur denitrator is tuned and running, keep an eye on alkalinity and pH. Alkalinity will be used up faster than without the denitrator in operation, so an increase of alkalinity buffers may be needed. A RedOx meter that can read negative values is a very useful tool for fine tuning denitrators. The ideal ORP range would be between -100 to -250 with -170 being optimum. Above -50 indicates too much oxygen for the denitrator to function properly, and below -300 indicates the water has reached anaerobic conditions, at which point hydrogen sulphide will be produced.
Perhaps other crew members may chime in here with their thoughts/ideas on setting up/fine tuning sulphur denitrators.>
<You're welcome. James (Salty Dog)>
James Miller
Okayama, Japan
PS. I am going to Kochi, Japan tomorrow to hunt for a small round belly cowfish and some Zoanthids. :-)

Re Denitrators And Nitrite 9/9/09
<Hello James, like that name.>
I am finally getting zero nitrites and nitrates out of the denitrator.
It appears my combining a rather long coil (7 meters of 6mm ID airline) was overly effective at removing the O2. This plus the double reaction chambers meant almost 10 meters of travel, so it went anaerobic. Speeding up the effluent with a small colony meant nitrite. I sped up the drip and allowed nitrite to escape into an ozone reaction chamber returning any nitrite back to nitrate. The increased flow appears to have allowed the colony to multiply as I can now process a gallon an hour with zero nitrates or nitrites.
I guess patience was the key.
<Very much so with these type systems.>
Hopefully I can now keep my nitrates low enough to keep my corals happy. I thank you for your advice.
<You're welcome, and thank you for the follow up.
James (Salty Dog)>
James Miller
Okayama, Japan

Mail 8/27/09
Hi Bob,
I downloaded a pic I found on WWM, taken in 08, Red Sea. Was the pic with the adult Emp. Angel amongst coral encrusted rock.
What a beautiful pic, crystal clear. Nice job.
<Ah, glad you're enjoying>
On another note, can you check out my response to the denitrator query?
No one took it so I thought I would take a stab at it.
<Will do so. BobF>

General Fish Question... DIY denitrator  8/8/09
My name is Terry I'm a great fan of your site, Thank you for all your help in the past!! I'm building a coil denitrator and I was wanding if it is safe to you
silicone and super glue on the interior chamber? Will it hurt any of my fish/refugium plants or effect my water quality? Thank you. Terry
<These are biologically safe/inert materials once cured. Bob Fenner>

Re: General Fish Question... DIY denitrator  8/9/09
I just want to start out by saying I think your web site is the best with the correct and accurate information!! I want to think you for all your help in the past, Thank you. I am making a coil denitrator and I was wanting to know if PVC cement is toxic to fish/refugium plants or hurt my water quality once it is dried? I put a pvc cap onto my cylinder and some cement dried on the inside of the cylinder where water is going to run. Is
that going to hurt anything? Thank you. Terry
<Terry, this material also is chemically inert once cured. BobF>

Re: 20K HID and Actinic Blue Light'¦now Kalkwasser and Nitrate -- 06/10/09
Hi Eric,
<<Hello Oowais>>
Thanks very much for your prompt answer.
<<Quite welcome>>
Normally I use deionized or distilled water to make Kalkwasser water.
But I recently noticed that the deionized water contains 10 ppm of Nitrate.
<<Odd, the deionization process should remove all traces'¦perhaps it is leaching from the containers>>
I would like to know if I can use seawater, with around 0 ppm, to make the Kalkwasser water?
<<I suppose you could'¦though I don't know what kind of result you will get/if the extra salt ions will cause any adverse reaction. Try it and see what happens'¦>>
I just made a coil denitrator and would like to know the output flow rate per hour of the water.
<<This is a balancing act'¦ Start with a fast drip and measure the output for Nitrate and make adjustments accordingly'¦you want as fast a stream as you can get with a 'zero' Nitrate reading>>
Thanking you,
<<Happy to share'¦ EricR>>

Re Protein Skimmer Queries Selection And Now Denitrators 3/4/09 James, Can't thank you enough for quick reply and great advice. <You're welcome.> Some food for thought to feed your interest on my PH levels ;) It reads 8.28 at night and in the day, drops to 8.22 but never beyond. Assume that is healthy right? <As healthy as a newborn.> I had a run around the shops today (forgot to mention that I live in Beijing, China). They don't carry Aqua C, Vertex or Precision Marine. Only the REALLY expensive Bubble Kings. <Excellent skimmer and as you say pricey.> But I did see a shop carrying a Korallin S-3002 Denitrator with the Eheim 1048 pump. Do you see this as a viable solution in nitrate reduction as well? <Yes, the design is based around the C-1502 calcium reactor and combines sulphur media with calcareous media and will give you a high level of nitrate removal and is rated for systems up to 400 gallons. The recirculation method is far more efficient than simple single pass filters. As it includes reactor media, the pH is fully buffered and enriched with calcium before being returned to the tank. You will not see any immediate drop in nitrates, but once the bacteria colonize the chamber (3 to 4 weeks), the unit is said to reduce 100 liters with 50mg of nitrate to 0 in 3 to 4 days. There are public aquariums that use this same method of nitrate removal.> My thoughts are that both the recommended skimmer and the denitrator are within the same price range and my end objective is only to reduce nitrates so either way seems fine. Do you think so? <Yes, in your situation, it is a very viable solution. I will ask Bob here for his thoughts on this type of reactor.> <<My thoughts on NO3 reactors are all posted. Some of these units can be made to work... RMF>> Now I await the wise salty one to speak :-) <No cracks so early in the morning, I have a cold and the laughter is making me cough. James (Salty Dog)> Barry

Re Protein Skimmer Queries Selection And Now Denitrators 3/4/09 Thanks James. Feel better. <You're welcome. You can read some customer reviews of the product here. http://www.marinedepot.com/ps_ViewItem~category~Korallin_BioDenitrator_S_300 2_w__Eheim_1048_Pump_Nitrate_Reactors~vendor~Korallin~SearchStr~~action~view ~idProduct~KL9113K~idCategory~FIFRISDN.html> Awaiting Sir Bob's endorsement before I plunge :-) <Yes, and HE, is the wise one. James (Salty Dog)> <<Mmm, more like a wise-n-heimer... Soitanlee. RMF>>

Sulfur De-Nitrator A make shift version, will it work - 03/03/09 I have been scouring thru your forums trying to find more information about these de-Nitrator. As of yet, it doesn't seem that anyone there has any more info than the basic explanation as to what it does. I have a 5 year old 75gal reef with a 40 gal sump <http://www.talkingreef.com/forums/diy-projects/8213-sulfur-denitrator-build.html#>/refugium. (most soft corals and about 8 med sized fish) and I am board <Heeee!> with so many water changes. I wanted to get into the Sulfur De-Nitrator for the ability to not have to change water so much and also to not be so darn particular when feeding my fish/corals (worry about waste/nitrates) I had also read that the ARM reaction to the acidic output will supply some calcium to lessen the frequency that I dose Kalk. <This is so> I purchased 2 ViaAqua Poly Reactors: ViaAqua Poly-Reactor (Multi-Media Reactor)<http://www.marinedepot.com/ps_ViewItem.aspx?category=ViaAqua_Poly_Reactor_(Multi_Media_Reactor)_Saltwater_Aquarium_Supplies_ Filters_Inline___Specialty_Filters_Phosphate_Reactors&vendor=ViaAqua&SearchStr=va3311&action= view&idProduct=VA3311&idCategory=FIFRISPR&child=VA3311> and: CaribSea A.R.M. Aragonite<http://www.talkingreef.com/forums/diy-projects/8213-sulfur-denitrator-build.html#> Reactor Media CaribSea L.S.M. Live Sulfur Media 1 Gallon I wanted to know if this setup will work, I was going to start with a VERY small amount of Sulfur (1/3 filled) in the first chamber and 2/3rds filled ARM in the second chamber. I was going to start with a 1 drip/hr rate <Mmm, what "drip" units? Likely adequately slow... a few gallons per hour will be fine> and adjust as necessary. (I run a 24hr PH<http://www.talkingreef.com/forums/diy-projects/8213-sulfur-denitrator-build.html#> monitor) I wanted to also know if anyone has heard any long term effects with running this setup, like Sulfur buildup in the main tank after months/years? <Mmm, not likely, no. Sulfur reactors have actually been "around" for several years (mainly in W. European use)... they are a tried and true technology> Since most pumps will have too much power for the 1 drip/sec requirement, <Oh, here it is> I also had thought about putting 6 foot of tubing from the tank to the 1st chamber to let oxygen dissipate before the sulfur chamber and a 6 foot tubing after the second chamber to the tank to make sure sulfur does not reach the main tank, is this over thinking it? <Mmm, I think so... but try this out and see> Also, do I need to create some sort of gas release value for any nitrogen output in the process? <No... this bit of inert gas will/would just be driven out, released to the atmosphere> Thank you for any help/suggestions, I will send pictures after the setup is complete. Gary <Please do Gary... along with snapshot/s of your water quality test data over time. Bob Fenner>

High Nitrates, Please advice High Nitrate 9/19/08 Wondering what you think of denitrators? <They work, although becoming less popular with the movement towards live rock and refugium systems. http://www.wetwebmedia.com/denitrification_erfaqs.htm> I've received different opinions on them and do have a high nitrate problem. My reading says 160 and it is not going down even after water changes. I rarely ever turn my lights on and do notice that my skimmer wasn't keeping up with my bioload in my 220. I'm upgrading to a Deltec AP851 from a Turbo floater multi 1000. Will this help? <It should help.> I do not over feed at all (about 4 times a week and most food is eaten). My system is 6'LX30"WX24"T and it houses a 3 large damsels, 2 horn sharks (18 and 15 inches) and has almost no LR and between 100-200 lbs or Live sand. <These will need a larger system sooner than later.> System has been running for 2 years and I also run a fluidized bed filter, 300 gal capacity wet/dry filter, 9w Coralife UV, and 1/2 HP chiller which keeps my water temp at 68 degrees. I do not use RO water but just ordered a unit. <If you are seeing no change in levels after the water changes, the nitrate is either so high that it is off the scale for your test kit or there is nitrate in your change water. The RO will be a welcome addition either way.> What should I do? <A denitrator could help, but I would take a look at the rest of the filtration first. A large sump/refugium with live rock and purposeful macroalgae growth will benefit your system immensely. The wet/dry and fluidized bed filters are notorious for leading to excessive nitrate production. > Thanks for the help and also my spec gravity is at 1.024, nitrite .25, ammonia 0, and ph 7.8. <PH is low.> (I'm using the API tests and will be switching over to ELOS as I have heard they are more reliable)Thanks in advance, AG <Welcome, some more links below on the above advice. Scott V.> http://www.wetwebmedia.com/sharkslvgrm.htm http://www.wetwebmedia.com/nutrientcontrol.htm http://www.wetwebmedia.com/refugium.htm

Re: Ammonia?  8/20/07 >Hi WWM, >I think i have a slight ammonia problem. I feed my fish and 30 - 60 minutes later my fish start breathing for air at the surface. ><Yikes> > I test the water and it shows 0ppm on my test kit. ><Might be low dissolved oxygen> > The next day the fish are fine and no more >breathing. It has been happening for about 2 weeks and it happens everyday >after i feed my fish. But yesterday my Chromis' started to breathe at the >surface and about 3 days ago one of my yellow tangs disappeared ><!> > and i have a >feeling he is causing the ammonia spike in my tank the last 2 days. Before >he died the Ammonia was kind of like an on and off thing. But now most of >my >fish are gasping for air. Is it unusual to constantly have ammonia going up >and down? ><Yes... insufficient biofiltration...> >I have these pouches in my tank called 'Maifan Stones' by 'SUN SUN'. Have you heard of them? ><Have now: >http://www.google.com/search?q='Maifan+Stones'+by+'SUN+SUN'&rls=com.microsoft:en-us:IE-Address&ie=UTF-8&oe=UTF-8&sourceid=ie7&rlz=1I7PCTA> >They are meant to lower ammonia and nitrite ><I would remove this material> >and i think this might be what is lowering the ammonia every time. If you have any idea what is happening i would really like to know urgently. >Thanks, Maison ><... what re the set-up, size, history of this system? BobF> Hi Bob, My tank is 6 x 2 x 2 foot, Multi SL protein Skimmer, UV Sterilizer, Reef Octopus Nitrate Reductor, 12,000l/h return pump, Tunze Pump in a Rock(9000 l/h of movement), <5 Nitrate, 0 Nitrite, 0 Ammonia on my test kit (Aquarium Pharmaceuticals), pH 8.2. My fish are: Convict Tang Blue Tang 2 Yellow Tangs(1 now) Desjardin Sailfin Tang Lawnmower Blenny Mandarin Dragonet 10 Chromis Flame Angelfish Longnose Hawkfish 1 Black Ocellaris Clownfish 1 Ocellaris Clown Haven't had any filtration problems before, it only started 2-3 weeks ago. Yesterday i noticed these grey blotchy patches on my black clownfish. His middle white stripe has a transparent looking blotch on it. Would you have any idea what it is? <I suspect something amiss with your Nitrate Reductor... I would take this off-line. Likely either the feeder stock is poisoning your system or some co-factor here.> I've been searching for it on the Internet and can't seem to find it. All my other fish look perfectly fine. I just bought a new rotating powerhead yesterday and i am going to put it in the tank today to see if it helps the oxygen level. What would be the best and most accurate Ammonia test on the market? Because i don't like the Aquarium Pharmaceuticals Ammonia test kit. Thanks, Maison <Look to Hach, LaMotte brands/manufacturers... BobF>

Rock Placement, Water Flow, And Denitrification - 08/07/07 Dear WWM crew, <<Greetings Hiro>> Thank you for your wonderful advice in the past. <<Most welcome, I'm sure>> As before I am writing because my reading on the matter (at your website and elsewhere) seem to have hit some conflicting advice. <<Much here/elsewhere comes down to a matter of (differing) opinion, agreed>> I suspect it's a matter of context and I am not grasping the subtle differences, but would love your help. <<Mmm maybe, or it may simply be as you have interpreted...one person saying one thing and the other person saying another. But I will do what I can to help...or maybe just cloud the issue a bit more with my own opinion [G]>> Usually, I read that desirable water flow means no dead spots. <<In agreement thus far...>> Better the flow, better oxygenation, etc. This, seems to make sense. <<Indeed>> However, in some posts on WWM I have read that such spots in and around the LR *is* what promotes denitrification, and is the objective of the LR as a part of the biological filtration. <<Hmm... I agree that one function of the live rock is denitrification, but I don't agree on fostering "dead spots" in the water around the rock. Aside from the accumulation of detritus this would promote, it seems logical to me to keep water moving around/in/through the rock for the purpose of denitrification...how else does the water get filtered if it is not made "available" to the rock? I think of it as just putting a bag of carbon in your sump versus placing a bag of carbon in a canister filter...which do you think is the more effective method of filtration? Granted this isn't an apples-to-apples comparison. The anaerobes performing the denitrification require very low-oxygen environments which would seem counter-intuitive to inducing high water flow, but the structure of the rock/the fact the anaerobes are deep within the rock provide the necessary environment so I see little benefit to allowing the water to "stagnate" around the rock. And even if for argument's sake we say the "dead spots" around the rock would foster "better" denitrification...I feel good/vigorous water flow "throughout" the system is overall more beneficial than any small "increase" in denitrification processes. The denitrification will still occur...>> Until now, I have been trying very hard to point the powerheads under, into, and behind the piles of LR in my tank, trying to flush out dead spots created within the LR mountain. <<I would continue to do this>> Even then, there are pockets that form, and I can't seem to get rid of them. <<Tis not an easy task. It is impossible to replicate the water flow on the wild reef...the sheer volume/weight of the water movement is staggering>> When cleaning out the tank, I force water through such areas just to stir up the debris and get it into the water column - so that I can get to it when performing water changes. <<This is a good practice...and a good augmentation to providing complete/thorough water movement>> Is this Wrong? <<Not in my opinion>> Should I be piling the LR and leaving the caves, behind the LR (where the LR is piled up against the glass), under the LR, well enough alone? <<Mmm, best not to pile the rock against the glass if possible as this does hinder water movement>> Am I actually hindering the purpose of the LR by trying to have sufficient water flow in and around all my LR? <<Not at all...do please continue to provide vigorous water flow>> I've seen many beautiful Reef tanks, with wall-to-wall LR across the entire back side of the tank. I've wondered how they clean under the rock and between the rock...what people do when things fall down behind a pile of LR (like a Turbo snail - who can't right itself). <<Many such systems I have seen employed some type of "spraybar" behind the rock to promote water flow>> In order to avoid this dilemma, I've piled my rock away from the wall of the tank, and have powerheads forcing the flow around and under my LR... <<I wouldn't change this>> I built my tank with larger chunks of LR just so that I can leave caves and spaces open - I thought that was suggested/implied by the information on aquascaping in your book. <<Indeed...I do think this was/is Bob's intent>> But should I be packing in between spaces with small bits of LR, to get as much density from floor to wall to surface within the water column? <<Not in my opinion. An "open" structure to allow free movement of water/the animals is best>> Thank you for your help in sorting out my confusion! Hiro in NYC <<I do hope this helps. EricR in SC>>

Re: Rock Placement, Water Flow, And Denitrification - 08/08/07 Thank you so much for your clarification! <<Quite welcome...hope it helped>> That makes so much more sense. It's what I thought, and what I'd been practicing... but I started to worry that I was actually making the LR less productive (after reading conflicting info). <<Understandable...but observing the state of your system likely also indicated otherwise>> As you see I've edited my Subject line - for my follow-up question. In the course of reading up on WWM to try to sort through my previous question on the aerobic/anaerobic issues and efficient use of LR, I found that you (i) usually suggest a refugium sump over wet/dry (LR, macro, DSB and lighting); (ii) though acknowledge that FO system users often still prefer wet/dry; and (iii) at least in some of the articles Bob mentions how FO systems often have little or no LR in the display tank. <<I agree on all parts>> I suspect you are seeing what I'm about to ask - hehe - so here is my question from this: If a FO system has little or no LR in the display, would you still recommend a Refugium Sump with LR and macro, over a wet/dry? <<If the vessel is large enough to hold enough rock, etc. to provide sufficient filtration then this would be fine. But more often than not FO systems are heavily stocked, often with messy feeders, and a wet/dry or fluidized-bed filter will usually prove more efficient/be able to adjust more quickly to shifting bio-loads...albeit with a higher residual Nitrate level and little to no capacity to reduce further to free Nitrogen as compared to a "live rock" filtration system, and hence the "thumbs-down" on the use of these units for most reef systems>> Considering the 1-2lbs of LR per gallon objective, <<Is a very "loose" rule-of-thumb...much like watts-per-gallon in my opinion>> isn't it unlikely/unfeasible to have a Refugium with sufficient amount of LR in the Sump alone? Indeed...unless VERY large in relation to the display (equal in size or larger). Though with a vessel outside the display one can "cram" more rock in to the same space without regard to swimming/growing room for the inhabitants of the display>> When you suggest a Refugium Sump with LR, am I correct in understanding that you assume the total LR is 1-1.5x gallon, or is the Refugium still better than a wet/dry, even if you have significantly less LR per gallon than optimal? <<A sump and a refugium (I prefer separate vessels re) are always beneficial but under most circumstances unless the display contains a large amount of rock, FO and even many FOWLR systems will benefit from the addition of ancillary biological filtration in the form of a wet/dry or fluidized-bed filter>> This is important to me, because I want to move some of my LR out of the display tank (for more swimming room). <<Ah yes...it is as important for the long-term health of the fishes to provide a suitable physical environment as it is to provide adequate filtration>> The dilemma, which I am trying to resolve, is should I move it into a refugium and add more LR, or if I can't have enough LR per gallon (the problem is the added water volume of the Sump requiring more LR over all! catch-22?) if I should consider wet/dry. <<Mmm...in my opinion the amount of live rock needed is based on the stocking level of the "display" and not the overall volume of the "system." The more volume the better, for sure. But you needn't think you need to add more rock/bio-filtration just because you have added more water volume...let your stocking density be your guide. But that said...if this is other than a reef system, I think the addition of a fluidized-bed filter is an easy, relatively inexpensive addition that will fill any "gaps" in your bio-filtration>> Thank you so much. Hiro in NYC <<Happy to assist. Eric Russell>>

R2: Rock Placement, Water Flow, And Denitrification - 08/10/07 Thank you Eric! <<You're very welcome, Hiro>> That makes it so clear! <<Ah good>> If I may, one last follow-up (why is that answers just create more questions?) <<An indication of an active mind...>> Your last suggestion was to go for a Fluidized Bed. <<Yes>> Between FB and W/D, I thought most advice on WWM was to go for W/D? <<Apparently my opinion differs [grin]>> Is there a reason you think FB has an edge in this specific situation? <<There is... A fluidized-bed filter is generally less expensive, more compact, and less prone to clogging/channeling versus a wet/dry unit. But you can use whichever you wish as both are very good at quickly converting nitrogenous compounds for FO/FOWLR systems. EricR>> Hiro

Sulphur bead nitrate reactor producing instead of reducing nitrate - 08/02/07 Hi folks, <Hi Rob.> I finally got around to building the ozone/nitrate reactor I emailed Bob about on http://www.wetwebmedia.com/redoxinst.htm. The beast has been built more or less to specification (photograph attached). In the bottom left you can see the nitrate test of the effluent. Oh dear. My tank previously tested at around 5 to 10ppm. After four days of operation it's now about 25ppm and climbing. The nitrate level of the effluent is immeasurably (at least by my Hagen test kit) high at well over 110ppm. The Cyanobacteria is growing incredibly quickly. I haven't yet fired up the ozone generators so really this is just 2 litres of pelletised, activated carbon, 7 litres of Sulphur and 7 litres of coral chips in series. The drip rate is around 5ml per second which is a bit high but still tolerable. This services around 500 gallons of moderately stocked and fed reef. So where's the nitrate coming from? I've tested each chamber and the nitrate appears only after the Sulphur. The Sulphur beads are home made but from quite pure (BP grade) Sulphur. <I'd mix some of the Sulphur with freshly mixed saltwater, move and aerate it for at least 24 hours and test for nitrates. I'd also test the carbon.> It's "making" nitrate from the water that passes through it. I've read the nitrate can spike during the bedding-in period of a Sulphur denitrator <Yes> but this kind of rise seems extreme. The Sulphur chamber effluent has significantly raised levels of both ammonia and nitrite and the pH has dropped half a point so presumably bacteria are metabolising dissolved organics passing through it. <Likely and possibly also material from carbon or Sulphur.> Why in the Sulphur chamber, though? The activated carbon has a much larger surface area for aerobic bacteria colonisation. Why aren't I seeing a spike after that? Is Sulphur a significant enough bacterial accelerant to cause this kind of effect? Can I expect a general consumption of dissolved organics instead of a discrete, mostly nitrate metabolising function using Sulphur? Many thanks in advance, Rob. <It's all a question ReDox potential as you know. To be absolutely sure what is going on, you will have to measure it. A denitrator of any type can only reduce nitrates effectively between -100 mV and -200 mV turning nitrates ultimately to gaseous nitrogen. Anything above -50 mV will reverse the process to ammonia->nitrite->nitrate just as in a standard filter and consequently produce nitrates (flow needs to be decreased, likely what you are observing right now). Anything below -300 mV will provoke bacteria to use up Sulphur and produce toxic compounds like smelly H2S (flow needs to be increased). These denitrator systems (if working properly will) are great to reduce nitrates in large systems, but as you see, the ReDox potential should be monitored manually or automatically to exclude toxic water in the tank.> PS, looking forward to bending Anthony's ear off in Durban in a couple of weeks. <I'm sure he is looking forward to that, too. Cheers, Marco.>

Denitrators. Does anyone know anything about denitrators? - 07/22/07 Hi, Does anyone know anything about denitrators? <Quite popular in Europe, especially in ancient times when live rock wasn't widely available. See http://www.wetwebmedia.com/denitrification_erfaqs.htm for answers to the most common questions.> and do you know which denitrator is the best on the market? <It certainly depends on the size and type of system. For small and medium sized reef and FOWLR systems up to 250 gallons (and possibly even larger) I'd prefer live rock, DSB and a large refugium (possibly with some macro algae), this combination is better and more cost efficient. A good skimmer will also be very helpful with any nitrate issue.> I have been looking at one made by Reef Octopus and it uses Sulphur. <Do they still build them? See their homepage. I do not have experience with this specific product, but the newer ones are very similar (disclaimer: manufacturers may disagree). A problem I see with some models is that the ReDox potential (see http://www.wetwebmedia.com/redox.htm if unknown to you) should be monitored and there should be some auto-regulation to avoid toxic water (nitrite, ammonia) getting into the tank. Usually simply some type of aeration is applied at the water outlet to ensure everything non gaseous is turned to nitrates again. What if for some reason the aeration fails or drops and there is no monitoring? As stated above, I'd go with other types of natural nitrate reduction for most home systems and leave denitrators with Sulphur to very large high end systems where live rock cannot be used in serious amounts.> Any help would be appreciated. Thanks, Maison. <Hope that helps. Marco.>

Denitrification ... writer, inventor of filters...   6/13/06 Bob: <Andrew> I'm a chemical engineer who designs wastewater treatment plants (for people).  I do a lot of work with biological nutrient removal, and have a lot of resources and knowledge on the subject. <Okay> I'm interested in designing a real nutrient removal system for fish tanks that I can market and sell to high end fish tank users in the Miami area.  My ultimate goal is to set up an automatic system that needs very little maintenance and no water changes. <A worthy task> I have looked around online, and your site is pretty informative, but there are some common misconceptions about denitrification that I have seen in most articles on the subject.   <Okay> I would be willing to write some articles on the denitrification process and exactly how it works for your website if necessary.   <Great! We'll gladly post them, possibly purchase for inclusion in our on-line 'zine... If useful, I'll gladly help you market them to the print mag.s with you> What I'm interested in is getting some data.  It has been years since I have had a salt water tank, and I'll be setting one up soon for testing, but I would be very interested in getting data of how much poop a fish produces in a day. <Variable... depends on species, size, environment, foods proffered... there are such fishery data for many food fish species> I can interpolate the data based on an experienced persons knowledge of how fast nitrate or ammonia levels go up with a certain amount of fish in  a certain size tank.  Something like ppm of nitrate per gallon per gram of fish number is what I need to do a proper design of a denitrator. <Have been involved in such designs...> Also I'm interested in anything else that would need to be removed from the system for proper water chemistry.  I'm not sure if phosphorus is a problem. <Sometimes... soluble phosphate can be problematical> The system I'm designing would remove bio solids produced, so solids buildup isn't an issue. Please call me or email if you can be of help or if I can help you out. Andrew Ball <Bob Fenner> Nitrate Control/Denitrator  - 4/11/2006 Hi,  <Hello Mike> I've been looking into getting a denitrator for my 180G fish only tank, but I am a little confused by my options and their effectiveness.  I've seen conflicting reports on them everywhere, even on your page I notice some people recommend them, and others don't.  Can you explain what type of denitrator is best? <None> (sulfur, bio, home made coil)  Also if I use a denitrator, should I also get a calcium reactor to help regulate the pH? Finally, are there any downsides to using one?  <Mike, personally I think denitrators are a waste of money and something else to fiddle with.  Nitrates can be effectively controlled without using such devices.  Read here and related links.   http://www.wetwebmedia.com/nitratesmar.htm> Thanks,  <You're welcome.  James (Salty Dog)> Mike

Sequential fluidized bed reactors in a marine aquarium - 2/28/2006 Bob and crew, <Jery> Great site!  (Although I have probably spent too much time on it!) <Is that possible? I hope not!> Despite having spent significant time on your site and elsewhere, I cannot find an answer to my question.  Recently, I noticed that a waste water facility uses an anaerobic fluidized bed reactor.  (Funny the things one notices when they get into this hobby!)  This may be a silly question, but I know very little about such things.  The idea started me to thinking, which leads to this question. I was wondering the following:  If a person was to run two fluidized bed reactors sequentially, would the second act as a denitrator? <Mmm, depending on flow rate, ambient DO... and digestible nutrient... possibly... to an extent almost all such surfaces present a degree of aerobic/hypoxic/anoxic-anaerobic media effect>   In other words, is the water that comes out of a fluidized bed reactor sufficiently deoxygenated to allow anaerobic denitrifying  bacteria to grow in the second reactor? <At some point, yes> If it does not work, it strikes me that it would be caused by insufficient ammonia or nitrites to consume all the oxygen.  Do you agree or would it have other problems? <Very possibly... I would move the resultant water NOT directly back to a system with biota present, but into a sump, area of extensive baffling... perhaps lit with photosynthetic life present... Do you understand the concern here?> This leads to a counter intuitive thought.  It is more likely to work in heavily stocked or even overstocked aquariums. (Honey, we are going to have to buy a whole lot more fish to keep the water quality up!  Dare to dream...) <Heee and suffer the consequences!> Thanks, A Hopeless Experimenter. <Years, okay decades back I worked on devising a sort of "clam shell" that would enclose a long length of polyvinyl tubing that would have a type of media wound inside it (Ceca-mat), sort of like a "pipe cleaner", with a low flow pump source, trying to achieve the sorts of ends you hint at here... couldn't "dial it in" sufficiently to disallow the "tinkering" with addition of carbon source to feed anaerobic digestion... to make such units applicable/saleable to aquarists (in honesty). Cheers, Bob Fenner> Re: Sequential fluidized bed reactors in a marine aquarium  - 3/1/2006 Bob, <Jer> Thanks for the reply.  I have a follow up question if you would be so kind. <Hotay> I think I understand your concern, but I want to be clear.  Your concern is that the water leaving the second fluidized bed reactor would be so carbon dioxide rich and oxygen poor that it would be dangerous to the biota? <Mostly, yes> Now on to my real questions.  In your reply you told me about your "clam shell" experiment.  Two things puzzled me and I am entirely too curious to let it pass.  First, you mentioned that you had to adjust it entirely too often to make in a reasonable solution. <Yes... flow rate and a ready source/substrate (carbon compounds are what I used, what most folks use) to otherwise feed the autotrophs> I have read that about other types of denitrators on your site.  But I have not read about how one knows how to adjust it.  How do you measure denitrification in real time? <Most such measures involve effects... the presence of nitrate... change in pH, dissolved oxygen...> Do the nitrate levels in the water change that quickly? <Can, yes> Or do you measure the oxygen levels? <Ditto> I have not seen oxygen meters in either online or local fish stores.  If I have to buy an expensive industrial meter, my wife will nix any experiments for sure! Second, you mentioned having to use a carbon source.  I did a search on your site and found a place where you said that sugar was such a source, but I could not find it explained.  What is that all about? <How to put this succinctly... the microbes involved are chemo-autotrophic... do "use" nitrogenous" material/s, but also require other essential nutrients, of which carbon (and/or its chemical family, e.g. S) are often a/the rate-limiting factor... "No carbon, no nitrification"> How is this different from denitrification in a deep sand bed? <Mmm, what is it you mean by "this?"... the processes are the same... some reaction pathways are more favored in one/the other...> Sincerely, Just Enough Knowledge To Be Dangerous <You're ahead of me. Bob Fenner> Nitrogen export 7/31/05 It is unclear to me how nitrogen export occurs in marine aquariums with live rock (LR) and deep sand beds (DSB).  While microscopic organisms in live rock and deep sand beds can absorb nitrogen from the water column or convert it to less toxic forms, how is the nitrogen removed from the tank? <not all is converted... some nitrogen is/can be off-gassed> If macroalgae is employed for nitrogen export, then nitrogen can be removed when excess algae growth is trimmed and discarded.   <correct> But how does one "trim away" the nitrogen taken up by organisms dwelling in live rock and deep sand beds? <No need to trim... it is fixed> Thanks very much. Regards, Paul. <Do search for more info at large on "nitrogen fixation"... I see 549,000 hits on my first google attempt. I hope you brought a Snickers bar <G>. Anthony>

Bioballs vs. Live Rock - 07/13/05 Dear All; <<Greetings>> Thanks for the great site! It has been a truly valuable source for me.  I am new to marine aquaria, but I have had fresh water systems for many many years.  It has been somewhat difficult making the transition, if not for your site it would have been an even more daunting task. <<"Thanks" from the crew...gratifying to know.>> I have been reading on WWM about the use of bioballs in a reef tank.  The general opinion seems to be that they should be avoided and the use of just live rock/sand bed in a refugium should be implemented. <<Agreed>> However, I have not read a sound, convincing argument about why bioballs act as "nitrate factory" and live rock does not. <<Really?>> Could someone offer a concise self-contained sound argument. <<Not asking for much, eh? <G> >> If a system has both live rock and bioballs then how does having the bioballs convert ammonia eventually to nitrates differ from the live rock doing the work? <<Ok let's see...concise...hmm...  The process is essentially the same for converting ammonia to nitrite to nitrate whether it's done by the bioballs or the live rock, as you have already surmised.  The difference comes after the conversion of nitrite to nitrate... The pore structure of the live rock (or the grain-size/depth of a sand bed) creates anoxic zones; not commonly associated with bioballs, that foster bacteria which can/will process nitrates converting them to nitrogen, which is then liberated from the tank as the bubbles you see rising from the rock/sand bed.  The bioball/wet-dry filters are referred to as nitrate factories because their end product is just that...nitrate...and they are so efficient at it even when used in conjunction with live rock they can overwhelm the live rock's ability to convert same to nitrogen.  Thus, most prefer to exclude bioballs from reef systems...though they can be quite handy for dealing with large/fluctuating bioloads in FO/FOWLR systems that can handle a higher nitrate load.>> Your time is sincerely appreciated. -Kenny <<Regards, Eric R.>>

Ceramic Beads, Denitrification, Editing 7/9/05 Bob, <Joe> In your recent daily FAQ, you wrote: "Well-made sintered glass or ceramic "beads", rings... actually are useful for anaerobic processing of nitrates... denitrification... the opposite, if you will, of the reaction series of bio-balls" My question is: WHY? It confuses me, because I would have thought that the oxygenation of the water, and not the physical nature of the media, would have been the deciding factor of the presence of denitrifying anaerobes. I did spend some time hunting WWM, so if you happen to know where this answer is, do you have a pointer? <... Mmmm, this the nature of the size of the pores, porosity... with little to no (hypoxic to anoxic) conditions in the teeny tiny spaces in this media, anaerobes are able to proliferate...> Now, on to editing, on this page... http://www.wetwebmedia.com/marine/setup/filtration/biological/biofiltr.htm ... you have a great big bold header reading "How Do It Know". I think it's supposed to read "How Do I Know". <A take off on "how it's s'posed to be"> Near the end of the article, you write... "...with nitrate being converted back to nitrate, then nitrite, ammonia and finally nitrogen gas." I'm pretty sure you didn't mean "nitrate being converted back to nitrate", unless I'm simply a Dum Dum, which has occasionally been known to be true. :) <No... tis an error. Will fix. BobF> Joe Kraska

Help with DIY of sulfur denitrification Hi, <Hello there> I'm a new visitor to your site and find it very helpful. <Ah, good> I am designing a sulfur denitrification system. I bought 3 six-foot clear plastic tubes that are six inches in diameter each. It has been suggested that start the water flowing through one tube filled with sulfur beads. Then I am to send the water through a second tube filled with calcium carbonate sand. This should return the water to normal pH while dissolving part of the sand thereby, raising calcium levels. Any comments? (Please try to limit your laughter.) <Mmm, not a laughing matter, particularly should you not remove all the sulfur by-product...> I need help to calculate the approximate water flow rate. I can calculate how long it would take water to pass through the first volume but do you know how long it will take to turn anaerobic? <Too many variables to consider... I would experiment here... with measured flow rate/s, a time device with a second measure... and either dissolved oxygen and/or pH as a measure of anaerobiosis> Do you have any suggestions for using part of the third tube to create a fluidized chamber? Could I use excess CO2 that comes from the sulfur bed? <I would have an "ammonia tower" arrangement... a reverse flow oxygenating device to blow air up as the water is cascading down plastic media...> Thanks a lot, Asa <Please keep good notes, records of your activity, thoughts here, and send along your results if you will. Bob Fenner>

Poison in the water?? Hello Mr. Fenner <Hi there> Thank you for the time that you are giving to solve all our mistakes and problems. <Welcome> I have all your books and I enjoy reading them over and over again and we still do mistakes. <Yes, I as well> I have a 240 Gl FO system. With all the necessary equipment that you recommend I have the system for 3 years know and it was going perfectly. I had fish which were transported from my smaller aquarium to this one and they were doing fine since 3 years. Lately I bought an Aquamedic Denitrator I fixed it according to their specifications and it was OK then after a certain while I realized some deterioration in my system Actually I didn't know why and suddenly fish started dying it was some kind of poisoning very fast fin rot and lashes in the stomach area and fast death. I lost all my fish within couple of days. I thought that it was a disease so I left the tank empty for a month and changed 30 percent of the water thinking that I solved the problem yesterday I bought two damsels to try the system they died the next day quick death. After a month without fish I am still having ( Cyano) the red slimy algae on my rocks I use RO water, the skimmer is not producing much anymore I think that's normal. Other than this I don't know what's going on. <Does sound/read like there is a toxic situation in your system> Yesterday I was reading your book just enjoying it. I realized you mentioned that Denitrator if working wrong they can give Sulfur H poison into the water and this was going on from the day I bought the machine so is it possible that I am poisoning my water all this time and not knowing about it or its another reason. <Does happen.> If this is that case if I stop the Denitrator will my water go back to normal? <Possibly... I would try draining the unit, removing it, trying another couple of damsels> I couldn't find any other reason what do you advice. <You might try adding a "PolyFilter" pad as well... in your water circulation path... and see if this extracts a colored material (a metal)> Thank you Regards Viken <Good luck, life to you Viken. Bob Fenner>

Re: poison in the water?? Possible denitrator issues Hello again I hope you remember my case, All fish died within 24 hours. I changed 30% of the water I tried 2 damsels, again sudden death.  I think I give up. I stopped the denitrator as you told me again changed 30% water, and put one damsel the same case , death in 24 hours. one damsel dying so fast in a 250 gallon aquarium ???? <Mmm, something very toxic> I'm totally confused an aquarium which was running perfectly for 3 years what could have happened. What do you recommend me to do. shall I start all over again. Thank you Viken <If it were me, mine, I would try first just draining all the water out, while gravel-vacuuming the bottom, refill with all-new water, let sit for two weeks... test for nitrogen cycle components... and see if this is enough to remove whatever (biochemical, chemical) there is toxifying the system. Bob Fenner> 

Denitrification Well it's my second attempt. Real sorry but my first lacked any particular question. O.K. Have a 215 gallon with 2 2028 Eheims. Was to be fresh but thinking FOWLR. Thing is the Eheims have a ton of surface area in the media which would provide great biological filtration right? or wrong?  <This can be very effective using a bio media such as Cell Pore. This is carried by Drs. Foster & Smith.>  I know a refugium or even a sump would be better but can I get this to work?  <Yes>  Thinking of a HOB skimmer like the Deltec 600 or similar. Fish will be big but not numerous predators. I'm kind of stuck with the filters and would like to use them if possible. Here is a link to Cell Pore. Very interesting product.  http://www.cellpore.com/  James (Salty Dog)>

De-Nitrator with new tank Hello Bob and Crew! <Rick> Thanks for all the time spent helping the rest of us sort things out! <A pleasure> We just bought a 200 gal corner bow front tank set-up from a local person who had never set up the system (almost everything is brand new!) with a beautiful custom built stand and canopy.  The tank and the trickle filter came from Aquariums by the Sea (seems like really nice stuff!) in FL.  Our question is about the set-up - we currently have a 72 gal tank with a 20 gal CPR PRO sump that has a refugium in it with a built in protein skimmer and we like the refugium, DSB concept, BUT the set-up for the 200 gal came with a 50 gal sump with a trickle filter, 1200 gph downdraft protein skimmer, De-Nitrator, Double Dosing pumps with a jug each of EVS Calcium and Alkalinity, 3000 gph dolphin pump to run the skimmer and circulate the tank (has a T in the plumbing) and we want to know if we should set- up our new tank with the stuff it came with, or should we consider changing the sump to hold or add a refugium, closed loop circulation or ?  <Up to you> This will be a reef set-up with MH, VHO and moon lights, we haven't picked out the entire critter list, but we like corals, clams and would have some reef safe fish, etc.. <Okay> We have been reading the CMA, Reef Invertebrates and much on WWM and we like the DSB, refugium ideas, etc. this set-up seems to be "high-class" (well made), but will it work? <Yes, can> We read what little we could find about denitrators on the WWM site, none really seemed to go into much detail.. <Most are more trouble than they're currently worth... as you'll see> This one uses methanol and the mfg claims that "this one works" and that many out there do not. It has 2 timers and a doser for the methanol and it does a complete flush every 24 hours to put the clean water back into the system and pull tank water in for cleaning...all on timers. <Try it out and see> Is anyone in the "crew" familiar with these set-ups and if so how they work? <Yes. No> This will be a major undertaking for us and we would like to "get it right" the first time, but we also understand there is more than one "right" way to do things. All comments would be appreciated... Anne & Rick - Oregon <Time to set it all up and fire it on over.... Bob Fenner>

Denitrifiers I have a 150 gallon saltwater fish only tank with extremely high nitrate levels.  I spent 400 dollars for the system and I not sure if it is working. Currently I feed the system for 5 minutes each day and it pumps back into the sump for 45minutes each day.... is this sufficient or should I be doing it more?<Personally, I think denitrifiers are a waste of money.  More can be accomplished by 10% weekly water changes and the use of a good skimmer.> I also have heard there is no such thing as too much filtration.. I currently have a wet/dry filter system but have seen the Fluval systems... would it be a problem to run both at the same time? <No problem, I would suggest using Chemi-Pure in the Fluval to help eliminate dissolved organics/nutrients. James (Salty Dog) Columbus Woodruff II

Re: Denitrifiers Thank you.... One last question... Should I take the bio balls out of my wet dry filter to reduce the nitrates? <Hello Columbus.  You should attack the source of the nitrates.  This will help more than anything.  Watch your feeding, 10% weekly water changes, consider the use of Chemi-pure.  This product will remove some things that a skimmer won't.  It won't hurt to take out the bio-balls.  Don't take them out all at one time.  Give the live rock a chance to adjust to the new bio-load.  James (Salty Dog)

Siporax versus live rock Good Morning; <And to you> Just a quick question that I hope you won't mind answering.  Recently I've added Siporax to the sump of my 90 gallon tank and I started pondering what the difference is between the effect that Siporax has as opposed to Live Rock?  If I understand correctly Live Rock uses anaerobic conditions to convert ammonia to nitrite to the final product of nitrate which then needs to be exported out of the tank. <Both media can produce such effect biologically, but the end-results don't require exportation. Materials are rendered into gasses and insoluble solids> I was intrigued by Siporax as the product claims to eliminate Nitrate as well. <Yes> How is it that Siporax is able to use the same type of bacterial colony to convert the ammonia to nitrite to nitrate but then goes the extra step to export or convert the nitrate to a nitrogen gas which is then exported from the water ? Sure appreciate the help, as always. Randy <Properties of both media... external, larger porosities that host aerobic nitrifiers, and deeper, smaller quasi and anaerobic regions that serve as sites for denitrifying microorganisms. The biggest "difference" between the two is that LR is composed of alkaline earth substrate (calcium, magnesium carbonates and more) that serve further to neutralize the reductive reactions of nitrification. Siporax is sintered (silica) glass... almost chemically inert. Bob Fenner> Future denitrification in dead rock. Hi I have one short question. Can (or will) live rock that has been dead be fully functional again? I understand it can when it comes to invertebrates (if other live rock is present) and nitrification, but how about denitrification? Thank you for your help. Anders <Yes... does become repopulated, function as a denitrifying field quite quickly... often within weeks. And re-populated with other life from some live live rock within a few to several months. Bob Fenner>

UGF plate in tank to create denitrification Bob, We've spoken recently regarding my new tank set up using RUGF <Reverse Under Gravel Filtration> with Crushed coral as substrate. I'm a newbie. As I keep reading up on all this stuff it seems that denitrification is one of the hottest topics when it comes to marine tanks. My question is.......instead of my original plan of a RUGF with Crushed Coral.....if I just use an UGF plate in my 75g FOWLR w/a few shrooms and softies, and use 1 1/2 of Crushed Coral, will it create a denitrification zone in the tank? <To some degree... would be far more effective with a deeper substrate level, depending on grade, three, four inches> And would regular aragonite sand be better vs. the crushed coral? <Of same average diameter, no> I'm not sure I know the difference between the two (CC vs. Aragonite) other than one is a larger size than the other but they have the same chemical make up. <Actually... aragonite/s are mined, consistent composition... calcium carbonate... crushed corals are collected inorganic matrices of organic origin that contain considerable "impurities" of use... like magnesium.>   I'm reading where CC seems to be a substrate that buffers well and holds the ph constant among other things. What do you think about denitrator units?   <... am a big fan. Bob Fenner> Thanks Don

Chemical levels  Hello Bob,  <Hi Nick>  I am pleased with your website. Have you heard of a denitrator device?  <Yes... anaerobic boxes typically... that are fed carbon solutions (sugars mostly)...>  It is supposed to keep your nitrate levels way down w/o having to do water changes. Will it keep your Ammonia and Nitrite levels down as well? Is there another device that will keep the ammonia and nitrite levels down? Where can you get these devices?  <Take a look on the Net using the term "Denitrator"... you'll find there are quite a few types of units made... most are a pain to work with... better to utilize other avenues at limiting accumulation of nitrates...>  Is there an electronic device to test your water chemical levels? If so where do I get one.  <There are a few companies that make electronic test equipment... take a look at Neptune and Aquadyne's lines... there are many others. Most are too costly, produce more fine tuning than is practical for the vast majority of home hobbyists>  What is the scope called that shows salinity levels and where do I get one?  <There are refractometers that measure salinity as well as a few other devices... most folks get by just fine by measuring specific gravity with a much less expensive hydrometer>  I heard that there is a new e-book on how to build and maintain your own marine aquarium, do you know where I can get it?  <Mmm, haven't heard of this tool. Bob Fenner>  Thank you so much and God Bless,  Nick Romano

Sulfur denitrification  Hello,  Sorry for the msg.? and thank you for your time.  <No worries and glad to help>  I was reading and I found material about the sulfur denitrification (using sulfur as media for bacterial colonies). I know that the best against pollution is dilution and the control of nutrients, but in my country (Argentine) is very expensive the RO water and  equipment, and for that reason I'm always looking for new method of improvement, and also I am a DIY guy. For that reason tell me what do you think about the sulfur denitrification..  <Quite popular in some countries in Europe... but virtually unknown in the U.S.>  MY system is 50 gal FOWLR with a few snails and a Condy (with 100W halogen lamp over), all over Crushed shell, no coral sand and DSB, because is too expensive.  Do you think that is better remove the crushed shells and leave the bare bottom with the LR in order to reduce the nitrate level(50mg/l).  <Mmm, that or make the bed pretty deep... several inches if the average particle size is more than 5-6 mm.>  I do siphon 5 gal every 2 weeks but is always the same , the level goes up.  Thank you in advance and sorry for my English.  Eckhard  <No problemo. Yo entiendo todo aqui. What are your actual nitrate readings? Have you considered making a denitrifying bed in a sump/refugium and tying its volume to your main system? Bob Fenner>

- Sulphur Reactor De-nitrification - Hi Guys. I am relatively new to reef keeping (11 months) and have just invested in an Aqua Medic Sulphur reactor in an attempt to reduce my rising nitrate levels (currently 50ppm). I have recently set the unit up at 1 drop per second flow rate while it matures. I have, however, noted that the instructions state that you should also pump the water that leaves the filter through a bed of hydrogen carbonate to neutralize the by-product of the process, sulphuric acid. <Sounds reasonable.> I assume that this has been suggested to avoid a reduction in PH levels?. <Among other things - alkaline reserve.> I have checked the instructions for other units and have not identified any similar units which state this as a particular requirement, however, they do state that PH levels of the water leaving the unit will be reduced. I would be grateful if anyone could advise on whether this is a requirement specific to the AquaMedic unit or whether all units require some form of secondary filtering to increase PH. <Given the nature of the byproduct of this type of reactor, I'd think some type of secondary reaction to reduce the strength of the sulphuric acid would be most useful.> My initial view was that I would compensate any effect on PH by buffering the water as well as ensuring that the return tube from the filter feeds into a high flow area of the tank. <For certain, you're going to have to do something... your pH will hit the floor eventually if you don't.> In addition, does anyone have any idea what the maximum flow rate through the unit is once the reactor has started to work. <No... should check with AquaMedic on that one.> I assume that you are not limited to 1 drop per second as maximum flow? <Probably not.> Any help would be much appreciated Thanks Jason <Cheers, J -- >

- Sulphur Reactor De-nitrification, Follow-up - Thanks for the quick response, <My pleasure.> looks like in going to have to go for the additional unit.  Better to be safe then sorry. <Agreed.> Cheers Guys <Cheers, J -- > Suitable sand? 2/24/04 Anthony, I must first say thanks for all the recent help, <always welcome my friend> I wish I knew as much as you about tank keeping!  I was reading in your book that you can use  a 5 gallon bucket full of sand with tank water flowing over it for extra  denitrification.   <yes... this is very safe and easy to employ> (My tank is set up and I don't want 5-12 inches of sand in my main tank.)  Can I use KENT Biosediment to fill the bucket instead of sugar sized sand?   <perhaps... but I've never tried it> Which would be more beneficial to reduce nitrate?   <I cannot say. I simply know that fine oolitic/aragonite works very well and is so inexpensive. I also have very little personal regard or respect for Kent products/brand> They claim it will also release trace elements slowly into the tank.  This is good, right? <I cannot confirm this> (I do know that over time I will lose some sediment due to it dissolving) Also you said it is not recommended to go more than 12 inches deep with sand, but in a 5 gallon bucket the sand will be about 16 inches, this is ok? <Hmmm... the 12" max is not set in stone, but a practical limit for illuminated displays. The bucket is not illuminated and not limited here> I really appreciate all the help you and your book have given me and I'm trying to lessen the amount of my questions by researching first. <its a better way to go my friend> Thanks and  have a great day PS what size tank do you have? <I wide range of tanks here at home and over at another family members house (for when I travel/am away). About 2,000 gallons total in saltwater at present> What kind of corals do you stock? <I prefer rare soft corals and odd invertebrates (cephalopods, Nudibranchs> Favorite fish or coral? <too hard to pick just one <G>. So many beauties in the sea. Kindly, Anthony>

New-Fangled Denitrator Thingy...? Hi Folks: <Hi there! Scott F. at the keyboard today!> Always new gadgets showing up on the market. This time its a Sulfur Denitrator. What's your take on this item, anything to it? Pro, cons, and etc. As always I appreciate you comments. Rick Luckert <Well Rick, I am not familiar with the particular denitrator that you're referring to here. However, I have seen a number of "denitrator" products on the market over the years, most of them reasonably effective, all of them seeming to require considerable maintenance and "tweaking" to do their jobs effectively! Frankly, I believe that a well-maintained deep sand bed, either in the display or in a remote location (a sump or refugium), is the best approach to denitrification. When coupled with regular maintenance techniques (water changes, protein skimmer cleaning, etc.), you'd be hard-pressed to find a better system to do the job, IMO! That's my two cents on the subject! Regards, Scott F.>

Monaco-style aquarium setup - 6/27/03 Hi! In the book 'Natural Reef Aquariums' by John Tullock <Very familiar with this book. I highly recommend it to all reefers and fishkeepers> a pretty good description and explanation of the Monaco-Style denitrification system; An underwater gravel filter plate, covered with screening, sand then another screening, aragonite, coral, LS and LR, etc. as any normal Berlin Reef Aquarium. Does WWM have any experience or comment on this technique of denitrifying? I am thinking about using it in a 75g reef tank. <I don't personally have a lot of experience with this style/method of tank denitrification although, I can see the science behind the set-up. I personally don't think all the layering and filter plate are necessary any longer. Much is known about the deep sand bed and more is being scientifically discovered as time goes on. I believe Rob Toonen is doing some experimentation and I would expect a report in a year or two. Live Rock is your major biological filtration system and add a sump to that and......well..........a beautiful natural reef system. Do use the google search tool on our site and plug-in "Monaco-style". See what comes up. Again, nothing wrong with this technique, but there is a more simple approach (less expensive also) that will do the same with a little less work. Do read through the articles and FAQs on our site about various setups and filtration methods. Have fun! Paul> Gene L. Louthan

Denitrifying bacteria Hi I was wondering I've started my 75 reef tank and I have half the tank with rock from my thirty I recently had setup am receiving 50lbs of pre cured live rock Fiji am planning on doing a high 1.030 salinity dip to get rid of all the pesky critters then chuck it in to my licking then let it cure let the ammonia spike then let the bacteria grow on my emperor duel bio wheel will this work? <yes the bacteria will establish itself on the LR the gravel and the filter> to let it cure in my 75 there's no life on the live rock already in here so this should be ok I also heard NO LIGHTS as it will grow algae how long till it grows the denitrifying bacteria thanks JM <It all depends, I would allow between 3-4 weeks and would check ammonia, nitrites often. Would not add any livestock until water checks out good (the tank is cycled), IanB>

Denitrators, Octopus Dear Mr. Fenner, <Steven Pro in this morning.> I was scanning through the websites on salt water aquaria, and came across your forum, and was wondering if you might give me some insight on denitrator units. <I don't like them. Too much hassle and expense when there are other alternatives.> Seven years ago I purchased a 125 gal. tank with a "Life Support Systems" trickle filter rated for a 250 gal. tank. It has 2 pre-filter siphon boxes on the back of the tank, an in the sump oxygen/ozone reactor, protein skimmer, and carbon reactor. I also have a (maybe you've heard of it) Terminator denitrator unit which uses a programmable pump to automatically inject methanol to feed anaerobic bacteria, sending nitrate levels back to zero before flushing water back into the wet-dry unit. I used this system for about a year without any problems before tearing the whole system down in preparation for moving to a new home. I had been remodeling a room in the basement for a recreation room where the tank was to be set up and am now ready to start my hobby once again. My question is this... Do you think that this system is overkill, or should I continue to use the denitrator unit I bought? <I would never recommend someone buy this setup, but since you have it (and it was working for you?) I would go ahead and use it.> I used to have a lot of live corals, clams, a few fish, anemones, and I kept an octopus, as I had a Plexiglas divider installed in the middle of the tank to house the octopus separately. This system seemed to operate fine but my octopus only lived about a year, which I am told was about its natural life span. <Yes, they are short-lived animals.> Any suggestions? <Really, you only had the tank setup for one year. It is too short a time frame to make an accurate determination as to whether the unit was functioning properly or whether the animals were thriving or surviving. I would be inclined to use whatever I could, but change the philosophy more to a natural system (liverock, live sand, protein skimmer, and vigorous circulation). You can read much more about this searching www.WetWebMedia.com or with Mike Paletta's excellent beginner's book "The New Marine Aquarium."> Sincerely, Jeff Lloyd <Best of luck to you. -Steven Pro>

Denitrification I have a 46 gal tank I like to use for a reef tank, I have in the past......I use a wet dry filter, with a Knop protein skimmer in the sump. My first question is this; I was nervous to do water changes when I had established my tank last time (before I moved), because I did not have a reliable source for low nitrate water.  <interesting... and sorry to hear it. But what did you drink/cook with?> However, it seemed that as long as my live rock was thriving (I had probably about 70 pounds at least) and I had some good plant/algae growth, the nitrates stayed down (I have a power compact with 96W bulbs, one white and one blue, seemed to keep things growing well). <eh... usually works for the short run... 6-12 months. But it is hard to run such a tank for several years without water changes. Very fortunate if you did. Uncommon> Can you continue like this, or do you almost always have to resort to water changes?  <water changes are needed at least monthly if not weekly (small)> I live out in a farm area now, my well water is probably 20 ppm nitrate per my tests, so unless I install a RO system, I'm not sure what to do, the water I set up is already high in NO3. I do have a little substrate on the bottom of my tank, but just a dusting, no more than 1/4" and mostly at the front. Any thoughts <sure... natural nitrate reduction with a deep sand bed (5+inches) of sugar fine sand. Do read more on this site archives and beyond about DSB (Deep Sand Bed/ NNR) methodologies> Can a skimmer remove nitrates? <indirectly by exporting nitrogenous waste before it degrades into nitrate> Thanks, Chris <best regards, Anthony>

Nitrate Reduction in Marine Aquarium Bob, <Steven Pro this morning.> I've read through all of your Nitrate FAQ's, but cannot decide how to best address the high Nitrate levels in my 75 gallon Marine Aquarium.. I moved my established tank a few months ago. W/in a few weeks all of my fish died from some kind of parasite. <Sorry to hear about it.> I hooked up a UV sterilizer and ran the tank empty for a month. <Good protocol> I then added 3 damsel fish. They survived for several months, so I decided to add a Yellow Tang, then a small Spotted Puffer and finally Dragon Wrasse and 3 small Hermit Crabs.. After several months of neglect, I did some water tests and found my Nitrate levels were at 40 - 60ppm ... I've had virtually no algae growth, but that my be due the UV sterilizer. <No, UV's only affect things that flow through them. You may not have enough of some other condition (phosphate, lighting, etc.)> I've since turned it off. In the last 2 weeks, I've changed 30 gallons of salt water out w/premixed salt water from my local pet store. However, the level has not dropped and I'm at a loss of how to get them down. <Is the saltwater from your LFS RO water mixed with a clean salt mix? Does it test zero for nitrates?> I eventually want to add a few invertebrates, so I have to get these Nitrate levels down. My System Consists of: 75 Gallon Aquarium Under gravel filter powered by 2 penguin 1140 power heads. Seaclone Protein Skimmer Fluval 202 Canister filter which returns to the aquarium through a UV Sterilizer. 30 lbs of Base Rock & 10 lbs of Live Rock. 3 inches of crushed coral substrate. I've researched several methods of reducing the Nitrates. Mangroves will not work, because I have a canopy w/lights mounted in it. <Mangroves do not usually grow fast enough to remove a significant portion of nutrients. Caulerpa is the "plant" of choice for this application.> A glass cover, is directly over the Aquarium. An external refuge for Mangroves or other Nitrate consuming plant life scares me, because it may flood my house if the power fails. <Not if designed and installed properly.> Live Rock is prohibitively expensive so a Berlin System is not likely to be an option. I'm left w/ two options. Option #1 Create a live sand system, by shutting down the UG filter and capping its lift tube holes. Remove all but an inch of substrate, put down a nylon screen and top w/another 2 - 4 inches of substrate. <You should not leave any of the old substrate.> Add my base and live rock back into the system and run only w/the Protein skimmer. My questions here are, will the UG be enough of a Plenum area? <Yes> Wouldn't shutting down the UG cause a large die off of bacteria creating a huge Ammonia plume? <Yes> I have no where else to keep my fish long enough to cycle the tank, so they would have to be able to go back into the tank w/in a day or two. Would my SeaClone protein skimmer and live sand/rock system be sufficient to support my live stock? <No> Option #2 Add a coil DIY denitrification filter between the Canister filter return and the Protein Skimmer. What would be your suggestion? <The coil denitrator would work, but is highly hands on as far as adjustments go. My preference would be to add a remote tank/sump with DSB and Caulerpa.> Thanks, Glenn <You are welcome. -Steven Pro>

Nitrate reducers Hi Bob, do you know of any type of equipment that will reduce nitrates? <Yes; DSB, Coil Denitrators, Protein Skimmers, Water Changes, etc.> I saw one on eBay that claimed to reduce nitrates and never have to do a water change again it says. Nforcer is the brand and it is a electrochemical nitrate reducer. It sound sort of iffy so just want to confirm my suspicions. <I believe it is a denitrator, not sure. These do work but are labor intensive, constant adjustments, feeding, etc. Nothing works like water changes, protein skimming, careful feeding, etc. -Steven Pro>

De-nitrification Filter Questions <<JasonC here filling in while Bob is away diving>> Having read your books and others I know you are not a big fan of these due to their finicky adjustment needs. However I am a gadget kind of guy and wanted to try one. <<I'm a gadget person too, but I'd classify most of these items as crap - way more trouble that they are worth versus the potential good they are advertised to produce>> I do not intend that it would eliminate water changes but instead might reduce Nitrates slightly between changes or slightly extend the time in-between. I have a 250 gallon custom made acrylic fish only. The Nitrate reducer is a flow through Aqua Medic unit which seems to be very well made although I quickly replaced the standard adjustment valve sent with the unit with a poly needle valve unit in order to get finer adjustments on the drip rate. I also have an ORP probe and meter hooked up so I could get some accurate data on the internal environment of the unit with a goal towards a target range of -200 to -300 mv. The unit is also supplied with "food" type bio balls. Interesting enough I am having a heck of a time getting the unit to go anaerobic even after three weeks or so. I have tied commercial food additions (Aqua Medic) without a lot of change. <<Ah ha... you are now discovering why these aren't really that much fun.>> Also, (per Moe) have tried a little sugar water (glucose) and alcohol (high test vodka again per Moe). The Vodka seems to drop the ORP pretty good but I have been reluctant to over do it. <<seems more complicated than it needs to be.>> Question, is sugar water or alcohol an effective food or should I just wait it out until the unit goes anaerobic on its own? <<If I were you, I'd get over this little gadget and move on to a sump/refugium loaded with Live Rock. No sugar water or vodka need ever be applied and you'll get a 100% natural Nitrate Reduction without complication.>> Thanks Randy-Las Vegas <<Cheers, J -- >>

Re: Tunze skimmers, Nothing To Do With Tunze Skimmers (plenums, denitrification) I always have a lot of concerns which usually end up in a form of a question and it is very nice to find someone to ask them to. This question pertains to plenums under the tank substrate. If the water goes stagnate and air is eventually depleted as this is necessary for anaerobic bacteria to do there thing. It would seem to me to only water to be denitrified is the water in the plenum and very little exchange would take place. <I am going to try to make this very simple, when it is actually a complicated chemical matter. Water would move between these two areas of your tank in an effort to seek equilibrium. Your main body of tank water has a high O2 level while the plenum water has a very low O2 level. But, this is all one body of water that would like to be the same across the board.> Also I have had an idea on a system to reduce nitrates and would be thankful if you would give my your thoughts on it- Using a 55 gal poly drum, place a large foam block in the drum, the foam block would large enough to just about fill the drum, inlet and outlet would be on the top of the drum, inlet water would filtered with a canister filter to prevent solid matter from entering the drum, drum would be kept in a dark room to prevent any plant growth. Idea being center of foam block will be a denitrifier. <Interesting idea but, I think this would become a mess eventually. Have you ever seen a trickle filter at work? No matter how well the water is prefiltered, there is always "dirt" settling at the bottom that must be siphoned out. That "dirt" is mostly dead bacteria that has sloughed off. You would have the same production of dirt in your drum but no way to remove it. FYI, you have this in DSB's too but you have worms, amphipods, copepods, limpets, etc. there to consume it.> Do chemical substances really remove nitrates from the water and are they worth using. <They may work, but not cost effectively.> Thanks again, Rick Luckert <You are welcome. -Steven Pro>

Plenum - to remove or not to remove? I have a 14 month old 40g Eclipse tank. Learning how to keep this in balance has been every bit as interesting and complicated as medical school, which I finished 4 years ago. I certainly find it easier to maintain a room full of premature babies on ventilators than to keep my tank in balance- the more I learn, the more I realize I don't know! <A couple of weeks ago, the premature baby comment would have completely freaked me out. Luckily my wife is now at 39 weeks and doing good.> The burning issue of the moment concerns my "plenum" which is not functioning as such. My tank is overstocked (early ignorance), with 12 goby/blenny type fish (ranging from yellow goby ~1.5cm to flame hawk to 2 alarmingly large Engineer gobies at about 12cm now). I have numerous different polyps (doing well), 50# of healthy live rock, no stony corals. It has a 55w power compact light and a Prizm protein skimmer that produces a couple of oz every 3-4d. I have been battling high nitrates since September. It started acutely with a dead snail and nitrates that leapt from 12.5 to 100 in 1 week, and things have never been quite the same since. In November, I took everything apart and put in a plenum (plastic egg crate, screen, 3" crushed coral topped with 2" aragonite). Initially I did see an effect, with nitrates again in the 5-15 range for a month or so. Then of course my engineer gobies started digging it up. I now have areas where the gravel is 9" deep, covering and killing a powerhead, and areas where the screen is visible. Nitrates have been about 20 for couple of months and just this weekend were 50. I have been changing 10-30% per week using your recommended water change procedures. My phosphates are also high, the worst was 1.0, now around 0.6. I have been using a Polyfilter since mid-January, and Phosguard since Feb. 1, and have started straining my food as you suggest. Through all of this, my polyps look good and I don't have any algae problems (hair algae was a problem in Dec., but GARF reef janitors took care of that completely). I don't have terrible ill effects from the nitrates that I can identify. Still, I am sure things would be happier if I could fix this. It is apparent to me that my plenum is not doing its job in its dug-up state, and in reading it seems I am at risk also for significant hazards related to a malfunctioning plenum. I have been thinking of taking it out, by removing all the tank contents, then vacuuming out the entire substrate, rinsing the bottom, and adding a 1-2" bed of live sand and replacing the tank contents. Should I remove it? If so, is this plan reasonable? What other recommendations do you have with regards to my nitrate problem? (I plan to upgrade to a 130gal with an Ecosystem-type filter perhaps within the next year, and transplant my current menagerie to that). Tracy Creek <Tracy, my recommendation would be to remove the plenum and go with 4+" of fine aragonite sand on the bare bottom of the tank. You are still going to have problems with your fish digging, though. My other recommendations would be to use purified water for water changes, grow some Caulerpa macroalgae in the display, get the larger tank to accommodate all your fish, or find another home for some of your fish. -Steven Pro>

Ich again; now denitrification Anthony, <Aloha! from the paradise in my mind. Anthony> Just a follow up note to say thanks..... alright, and a few more questions.... <OK> Thanks much for the insight. All is going well in the quarantine, and I've learned a valuable lesson about adding make-up water.  <good, do pass along what you learn to others in kind> I had been just judging temperature by approximate feel, figuring that 1 or 3 gallons in 70 shouldn't make much of a difference. Fortunately, I asked for help before I lost a fish to my ignorance. <a common mistake and symptomatically evidenced e.g. by all the many such keepers with blue hepatus tangs (Ich magnets) who treat water the same way <wink>> While I have your ear... er.. eye.... I have yet another question. This time, it is about substrate. Early on, I was given some bad advice. Actually, the problem is that I didn't know enough to analyze the advice of the LFS - I continue to get bad advice, but have learned to ignore it. I purchased about 1 inch of very fine aragonite sand with the aquarium, and was instructed not to rinse it (who knows why??).  <actually not necessarily bad advice...although messy, the fine aragonite dust dissolves easily and greatly assists the pool of alkalinity in your system> After a few weeks, I was finally able to get most of the silt vacuumed out - until then, Andy movement would cloud the tank for hours. I was then told that this fine sand isn't as good as coarser substrate,  <I totally disagree> so I mixed in a bag of Seaflor. It has many shells over 1/2" in it. The total depth is now about 1" or a little over.  <ughhh> I still wasn't too concerned until recently, when I decided to go through and strain out some of the bigger pieces. Straining released many small bubbles. They had a faint sulfur odor. Not knowing what to do, I sifted through all the sand to release the bubbles.  <not a crime> Do you advise me to abandon the Seaflor?  <pick one grade or the other an stick with it. In either case go over 3" or stay under 1/2 depth... in between causes problems as you've noticed. Pick fine for denitrification or more course for "bugs". Personally, the coarse is harder to maintain IMO.> I have 2 more 44lb bags, but don't want a detritus trap.  <which you will get without good water movement, skimming and detritivores> Do I need to first strain out the majority of larger shell pieces and add more fine sand? Also, since the sand is very alive with 'pods, should I mix the sands together as I add, or just pour it in on top? <would be best to do a quick tank break down, remove live sand, drop new in and place old back on top. Not as bad as it sounds with a fast water pump. Jason C here on the crew just did it to his display to catch a fish for dipping and drained, restacked rock and refilled the tank in slightly more than 30 minutes. The key is a large drain tube (1" is fast!!!) and a fast water pump for return> Another quick question. I have a large piece of tufa rock, and it has is getting coralline and green algae on it. I also see some copepods on it. eventually, I guess it will look just like my live rock, but will it ever have the same biodiversity and filtering qualities? <in time yes> Thanks a lot - this is one hobby where knowledge is so important, and yet so difficult to gain without your help. Daron <our pleasure. Anthony and crew and WWM>

Sand Confusion: Aesthetics or Denitrification? Anthony, I'm confused about the proper depth of substrate. Below is what you said in one of your letters. I don't get it. It seems contradictory. What's best, 1/2 inch, 3 inches, or 5???? Your words are in the red. Thanks! Pam PS I'm really not trying to be confrontational, I just want to understand! <I figured I would answer your question because I am here and we have pretty much the same point of view on this subject. If you have no sand, zero inches deep, a bare bottom tank, you are OK. As you add sand, you are OK until 1" deep. At this point all of the sand is aerobic (contains water with oxygen in it). As you go over one inch, you change from a completely aerobic environment but not to a true Deep Sand Bed (DSB). Deep is the imperative word. You do not get all of the benefits until you reach 3" or greater. In between 1 to 3 inches is a sort of no man's lands for denitrification. I hope this gives you a better understanding. -Steven Pro>>The substrate is about 1/2 inch in the front and increases to about 2 inches in the back. <dangerous in my opinion. Too thick to be aerobic but not thick enough to be helpfully anoxic. Just dangerous, and the reason why so many other reefers have inaccurately faulted "deep" sand beds. The rule stands at 1/2 inch or less, or more than three inches (I prefer a five inch minimum for denitrification. Anthony>

Thanks! (ceramic filter media/marine, clownfish production) I wanted to thank for your previous advise on placing ceramic media into the sumps of my wet/dries. It has made all the difference. <Ah, good... an expensive, one-time purchase (of this media), but well worth it> I'm running three systems composed of four 50 gallon tanks filtered through central wet/dries. The systems house four mated pairs of clowns each. The total fish load on each system is about 18" - 20" of fish. The Nitrate was problematic at times causing micro algae nightmares. Since the objective is to disturb the clowns as little as possible and get them to spawn on ceramic tiles and not rock I decided to forgo live rock.  <Yes... good idea... commercial production facilities should have as few "variables" as possible to manipulate, have to monitor, care for...> I'm down to one micro algae cleaning per month an a 15% water change every other month. I even added Top-Fathom 200A skimmers to each unit and shuffle a Ocean Clear carbon module around every so often. The nitrates are down to 2.5 parts per million. Unbelievable! Thanks again. Jeff Lawson Eco-Tropic <Outstanding! Looking forward to seeing some of your Clowns in circulation... soon. Bob Fenner>

Re: nitrates high! Dear Bob, OK now I'm REALLY confused. I quote you from the site you referred us to: "by using a typical wet-dry you will find a surplus of nitrates produced... and need to find ways to rid the system of the same... Instead, more "balanced" filtration approaches like using live rock, macroalgae, a mud sump... won't." Where do you describe the "mud sump"?  <Oh... let's see... do need to write a complete "piece" about these... How about here: http://wetwebmedia.com/mudfiltrfaqs.htm Please read through these FAQs and use the Google search feature on our site (WetWebMedia) with the words "mud", "sump", refugium, Leng Sy...> Isn't our crushed coral what they call a deep sand bed that has denitrifying bacteria? <If deep enough, not too-circulated, depending on grade, composition...> Would rustling through it disrupt this even if there is detritus in it? <Yes, to some degree> Everything I read said the trickle, while expensive, was the safest way to go (aside from a totally LR system).  <The "safest" way to go about what? Live aquatic closed-system filtration? Depends on many qualifying criteria, but not the "safest".> If we remove the BioBale, how will the ammonia be broken down?  <By nitrifiers elsewhere in the system... once going (cycled) there are plenty> How will LR do anything different from the BioBale? What's the best course to transition? <All this posted on our site... Please read: http://wetwebmedia.com/liverock1.htm  and beyond in the "Curing LR" FAQs sections> Last night, we vacuumed out a huge amount of black gunk under the BioBale. Hopefully we did not kill any helpful bacteria (or that gunk wasn't anaerobic bacteria). Nitrates are still sky high. I'm reluctant to change much more water since it's now approaching 50% in 3 days. <Not clear to me here... what is approaching fifty percent?> If we go out and buy lots of cured LR, won't a lot of that die in the transition and make matters worse? <Some die off, but likely no problem.> Then, we REALLY need a protein skimmer, right? Even, then, isn't that too traumatic? <Do you not have a skimmer currently? You very likely would/will benefit from ones use> In answer to your light question, our light is 4x20 watts (2 actinic, 2 full spectrum). Can LR survive OK on that? <Yes> We planned to be fish only (except our hermit and cleaner shrimp). It gets hot and we did not want to go metal halide/chiller. <Do try at least "some" live rock... you will not be disappointed I assure you> I can't seem to find a place that sells macroalgae. Where do you get that stuff. I've been hearing about some Caulerpa ban??? Regardless, I'm sure our little tang would love to snack on it. <Do check with the etailers posted on the WWM Links Pages> You just can't win. Sorry to always be so discouraged. Even if our system crashes, it has be 8 months of happiness (in between the crises). Thanks, Allyson <Ah my friend. You are on the brink of clarity. Do keep your eyes on the prize and study. Bob Fenner>

Toadstool help and Aqua Medic Hi Bob, Once again I am emailing you for some more help! My fish tank is the one at http://www.cia.com.au/winone <Nice pix, layout... Anthiines sold to you as "starter fish"? Yikes> I have since added a lot more rock to the fish tank but I have not updated my pictures yet. The reason I am emailing you is because I have no idea when it comes to corals. I brought some corals that inflate (e.g. bubble corals) and they are doing great :) <Yes, Plerogyra are great beginner corals> I purchased two toadstools and shortly after I put them into the fish tank they shed their skin and every few days to a week they shed their skin again.  <This is normal> I use a turkey baster (it's like a big eye dropper) to gently blow water on the toad stool so that the loose skin comes off. This makes a mess in the fish tank as there is dead skin and what looks like white powder everywhere. This settles and disappears in about 30 min.s. Today, to my horror, one of the heads on one of the toad stools fell off. I picked up both stalk and head and disposed of them. The other toadstool looks fine. It is a different looking toadstool to the one having problems. The one that had problems had a short stalk and the one doing fine has a long stalk. The heads are about the same size. <Shape more dependent on physical conditions (circulation, lighting) and nutrition than species...> Can the dead skin coming off the toadstool pollute the fish tank?  <Yes, if too much in too small a volume of water, or if quality is otherwise compromised... These soft corals can produce considerable terpenoid pollution... engage in real chemical battles with other stinging-celled life forms...> Why is there dead skin coming off these corals? What can I do to keep these corals happy? <This is a "cleaning mechanism"... not to worry> What corals are good for a beginner? <Please see the beginnings of coverage of the soft and hard/true corals posted on our site: www.WetWebMedia.com and the associated FAQs files, and in particular the references listed there> Many thanks for your help :) Warmest regards Lucien Cinc PS: I had to remove the denitrator because it started to smell bad. <Yikes, good idea. Am not a big fan of these units due to these unpredictable qualities...> I tried my best to get hold of the orb computer to control the denitrator, but even AquaMedic themselves in Europe ignored all my attempts to contact them. I was NOT very pleased with Aquamedic at all :( <Really? Am very surprised... this is a great company (saw their German representatives at Aquarama in Singapore a couple of weeks back... Would you mind if I forwarded this message to their U.S. division?> PPS: I have also removed the UV light as I believe it is doing nothing. I was wondering, if the corals are filter feeders, would a UV light kill the food that the corals need to eat? <To some extent yes... if your system is otherwise "going well" and firmly established I would eschew the use of U.V. as well. Bob Fenner>

Re: toadstool (and Aqua Medic) help Sure. If there is a chance that I can purchase the orb computer + probe + solenoid + black tubing + Deni-balls I would be willing to give the denitrator another try. I am not sure if the orb computer requires main power? <Hmm, me neither... have you checked their website? It's on the WWM sites links page> In the US it's 110v but in Australia it's 240v. If it's just a simple A/C adaptor down to 9v or something similar then I would be happy to purchase all the above from the US. <Not a big deal as you know> I even called the Australia distributor with no luck at all. They did not even want to talk to me, instead they wanted me to ask my LFS to call them. Every LFS I have asked tell me it's an impossible bit (i.e. the orb computer) to get. I was told there is going to be a 4 month wait just to get Deni-balls! What was I supposed to do in the mean time? <Contact the manufacturer... I am going to ask their US rep. to respond to you> How is AquaMedic supposed to sell things in Australia when they can not get any stock over here? <Got me...> Thanks for all the info on toadstools. I'm pleased the skin shedding is normal. When the head fell off the other toadstool I was very distressed. I will check on WWM web site for more beginner corals and stick to them for the moment :) <Ah, good> A very warm thank you for all your help, my friend :) <You're certainly welcome. Bob Fenner> Warmest regards Lucien Cinc

Re: Aqua Medic assistance Dear Bob, thank you for sending me a copy of this mail and giving me a chance to take care for Lucien. I have pushed our Australian Distributor to help him. <Outstanding! Will post your timely, positive response after his on our site: www.WetWebMedia.com. My appraisal of your products, Aqua Medic, AB Aqua Line stands. Excellence. Bob Fenner> best regards Manfred

Re: AB Aqua Medic U.S. Dear Mr. Cinc, I received an e-mail from a friend of yours Mr. Fenner. I understand that you are having trouble finding equipment to work with the nitrate reducer. The egg smell that you referred to is hydrogen sulfide this is caused by over feeding the unit and the Redox potential is to low to correct this reduce the feeding rate and increase the flow rate of the unit. As to where you can purchase the Redox controller and probe. There are 2 types of probes that we carry for the Redox controller one is for a low pressure system this unit has 2 clips that hold the top on and then one for a pressurized system this unit has 8 clamps holding the top on. Where to purchase the Aqua Medic line of products customaquatic.com this is a company I have been dealing with for some time and has a good reputation. You can call 1-800-397-7238 and ask for Todd and he can answer most of your questions as well as give you prices. If you have any other technical questions about our products please contact me directly by phone at 1-866-419-0086 or e-mail at AquaMedic@ev1.net or jutley@ev1.net. Thank you John Utley AB Aqua Medic Customer Service AquaMedic@ev1.net Toll-free 866-419-0086 Phone 281-419-0086 Fax 281-419-0502 <Again, outstanding. And do want to second the referral to Todd (Gabriel) of Custom Aquatic. I know him to be professional/very customer service oriented. Bob Fenner>  

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