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FAQs on Sulfur-Based Denitrators, Denitrification

Related FAQs: Denitrification Gear 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

Xport NO3 Product; Sulfur        7/1/17
I was in my LFS yesterday and was told about Brightwell aquatics Xport NO3 product which comes in a few shapes and sizes. It is a porous media containing sulphur which sits in a low flow area of a sump and denitrifies they tell me.
<Well-stated; and yes to there being such sulfur products. Best used in reactors... where they receive more circulation>
I can see no references to it in the wetweb pages and though there are threads on it elsewhere the question of does it actual make a significant impact on NO3 remains largely unanswered. I do not want to waste my money as this hobby is full of 'miracle' products.
<I think what little we/WWM have is likely archived here: http://www.wetwebmedia.com/SulfurDenitratrF.htm
I have a 180 gal FOWLR which despite water changes always has high NO3. I want to eventually keep some soft corals which requires me to sort out my water parameters.
<There are a few approaches. Am a bigger fan of natural methods... deep DSBs of fine material, RDP refugiums with macro-algal culture....>
I have tried vodka dosing and biopellets in the past, Cyano loved them, no other change. I have a good skimmer too, Bubble Magus curve 9. I have reduced my tank PO4 to 0.5 ppm with ferric oxide which greatly reduced the
nuisance algae but though the PO4 is not rising the algae seems to have found a new lease of life. I have read this can be due to PO4 leaching out of my live rock but I'm not seeing PO4 increases when testing?
<Likely being "scarfed"/scavenged readily by the algae/Cyanobacteria... a dynamic process>
With denitrifying media low flow is desirable but no flow is pointless.
<Ahh; again; well-stated>
As sump space is limited I was wondering if putting such media in the bottom of the overflow chamber is an option?
<Yes; tis one... though do read the citation above, consider a chamber with directed flow>
I have no idea what the water turnover is there though as the weir pipe draws from the surface of the overflow chamber about 1.5 ft higher up. Thanks for your time and help,

Nitrates gone wild!       3/6/17
Hello, and thank you for what you do.
<Hi; welcome Karen>
You've been a great resource to me over the years - but shamefully, not in the last few. which is why I am
writing today. I will try to give a bit of history without writing a novel.
I have a 225 gallon tank with probably a 30 gallon refugium and an additional 40 gallon sump. I say probably, because I upgraded from a 90 gallon in 2009 and I truly don't remember all the details. Tank has
approximately 300 - 400 lbs of live rock and maybe 200 lbs of sand (all was purchased from a company called Tampa Bay Saltwater). There's between 2 - 3 inches of Miracle Mud in the refugium along with some of the above mentioned live rock. I was very involved in the hobby until probably 2013 or so when a number of things happened (including the earlier death of my husband) to draw my attention away.
At some point, all of my corals died and I was left with a fish only tank - some of the fish having been in the earlier tank.
We (the fish and I) kind of limped along until last September 2016 when my lighting system failed. I had one of the first LED systems - you may remember the Solaris? - and it finally bit the dust. At that point I had these 8 and 9 year old fish (Regal Tang, Saltwater Tang, GSM clown, 2 Ocellaris clowns, One Spot Foxface, and a foot long Engineer Goby) and I had to make the decision as to whether to rehome them and dismantle everything or sink some money into the tank. I chose the latter and replaced the lighting system and had my local LFS who has helped me throughout the years, come and do a thorough cleaning and reboot (so to speak) of the system.
The LFS is also using my tank for some of their larger soft corals in hopes of later fragging them - or maybe they're just being nice because I've been with them forever.
Of course, within two weeks of replacing the lights, both my skimmer pump and main pump also died and had to be replaced.
After all that happened, and after several water changes within a couple of months, my Regal Tang got a mild case of ich. Acting on the advice of the LFS, I treated the tank with Kick Ich
<Ughh! A placebo at best. See WWM re this sham/scam>
and upped the feeding, varied the diet, added Selcon and VitaChem to keep the tang's immune system up.
<These will help>
I realize that's not the treatment of choice but I've been out of the hobby for a long time and, well, insert whatever excuse you can think of. At the time, the water was tested and everything was within normal limits but the
nitrates were very high (around 100) but that was attributed to all the stirring up and the feeding.
<Likely so>
Added Chaeto to the refugium and a carbon/GFO reactor and UV sterilizer. Ultimately the tang cleared up and presumably all was well for the next 3 months. I added a little ORA Orchid Dottyback and she's doing great - except that she was so small I continued to overfeed to ensure that she was getting food. Please note that during all this there wasn't any further water testing going on, but all the fish (even the Regal eventually) were fat and happy, the mostly soft corals thriving, and the water looked great. I'm running a skimmer, the UV sterilizer, and the carbon/GFO reactor. I have a moderate CUC consisting of a couple serpent stars, 50 -100 various snails, and a few Peppermint and Skunk Cleaner shrimp. So that's the history, and here's the problem.
I purchased a Mandarin and placed him in the tank, thinking that an 8 year old tank with lots of live rock, etc. would surely support him. He's a big guy, approximately 3+ inches. But I started thinking that he was looking
thin. So I bought some pods and put some Chaeto in the refugium. Then I bought some more pods. Then I bought an additional 50k pods and some phytoplankton and he still looks thin to my mind.
<I'd place the Mandarin in your refugium for now; likely interstitial fauna there... AND I want to make sure and mention that I'd increase the depth of the DSB there, AND run the lights/lighting there alternating with the main/displays (RDP)>
So I had an epiphany (I know, I know) and tested the water and the nitrates were very high (100 ppm). and I'm now freaking out because there's no way to know how long they've been that high - could have been for a long time or since I started paying more attention to the tank and began way overfeeding to bolster the tang. I also don't know if the Kick Ich treatment killed a lot of the beneficial bacteria or the existing pods or ..
<Perhaps... but... I would NOT obsess re the high NO3. It by and of itself is not a major concern; how to put this: OFTEN what such readings "co-interpret" is an abundance of other ills; high dissolved organics period, low DO, high BOD, low RedOx...>
Thus far I've cut back on feeding, am upping my water changes (but am somewhat at the mercy of the LFS who does my water changes)
<Mmm; I'd take all this back. Do the maintenance myself>
and I started the Prodibio Bioclean S on Friday. I've also added more flow and I took some of the live rock out of the display and put it in the refugium. And now the Regal Tang has started flashing on the glass and acting
differently - but only when the lights are on. Appetite is still good and there are no spots, but she's banging up her head a bit. I don't know if that's oncoming disease or just a stress reaction to the change or both.
<Can't say>
The guy with the LFS that's doing the water changes is concerned about the tank because the rock is sitting on egg crate and he believes that that is contributing to the nitrate issue by allowing detritus to accumulate, especially under the rock.
<Possibly.... I might well remove it in sections; even half during one maintenance interval, the other next>
So now I'm at a place where I don't know if I should dismantle the tank and try to remove the egg crate - and likely stress my elderly fish beyond the limit; add more sand on top of the existing sand; add a sulfur denitrator, or ..?
<Or all three...>
I know I need not take a scattergun approach and randomly try a bunch of different things (I already feel like I'm starting to go down that rabbit hole). Parameters today (water change about 48 hours ago) are: Ammonia and nitrites 0, pH 8.2, Alkalinity 11.2, Salinity 1.25, Calcium 480, Magnesium 1280, Phosphate .25 and Nitrates 160. Attaching a few pictures of the tank so you can see the amount of rock, sand, etc.
<Actually; looks fine macroscopically>
Any guidance you can provide would be very much appreciated. I'm sorry for the long email, but I was trying to cram in 8 years. And again, thanks so much for all the valuable help you provide.
<Thank you for writing, sharing. I would proceed as mentioned and hinted at. PLEASE do communicate if this message is not clear, complete and/or you have other concerns, developments. Bob Fenner>

Re: Nitrates gone wild!      3/7/17
Thank you so much for your quick reply, and thank you for easing my panic. I've read through this several times and I'm trying to come up with a plan - additionally, as I'm sure you saw in the pictures - I have a Sailfin Tang, not a Saltwater Tang �� I also have a few further questions, if I may ask?
<Go ahead>
I'm thinking that prior to moving the Mandarin to the refugium, I should increase the depth of the DSB as advised, and since it's completely made up of Miracle Mud, is that what I should add rather than sand?
<I would CAREFULLY (with the sand washed, damp... in a plastic hand-sized container) lay the new sand atop the mud. The latter will dissolve, decompose for the most part in time; and do some good here>
I mentioned three possibilities (removing egg crate, adding sand, and adding a sulfur denitrator) and I interpreted your response to mean that it would be a good idea to do all three?
<Yes; any or all>

Removing the egg crate can be done although it will be a major undertaking, particularly since some of the rocks are huge (probably 30 -40 lbs). I'm worried about the stress on the tank and the stress on the fish in proceeding in that direction... but if it needs to be done, so be it.
<Doesn't "need" to be; just would be better. The other measures mentioned above/prior would do ninety some percent of what can/could be done to improve water quality here easily>
My preference would be to add more sand without removing the egg crate,
<Then that is what I'd do>
but I don't want to waste the money or the effort in adding new sand if I'm only covering up the problem.
The sand in the tank is not quite a crushed coral but looks a bit like it, only a tad finer ... as described by the website where I purchased, it's ..." harvested well offshore in the ocean to be clean of pollutants and silicates. Live sand collected in this manner will be a mixture of sand, shell bits, corallines, bivalves, starfish, snails, and many organisms not visible to your eye". Would you suggest ordering more of the same or using another sand?
<More of this, finer in grade if available... most under 1 mm diameter>
And the third option is the sulfur denitrator. I've been reading up on them - but is there a specific model that you would recommend?
<Mmm; hold off on this till the other work is done and a month or two has gone by. Again; this is what I'd do>
Is there anything I have missed?
<Not that I perceive>
Again, I'd really like to thank you for your assistance with the tank. I get ridiculously attached to these little creatures and I really do want to provide an appropriate environment for them, despite appearances to the contrary as evidenced by my neglect the last few years.
<A pleasure, indeed honor to share with you>
Despite that, they've hung in there with me ... the Foxface is actually the first saltwater fish I purchased well over 10 years ago.
We all thank you.
<And all are welcome. BobF>

Sulfur denitrator... input diff. than WWM; but what is it?       1/26/15
Belgian Anthias is the name I use on several forums and I propagate the use of BADESS ( Biological Autothrobe Denitration by Elemental Sulphur) to solve the nitrate problem for ever.
<There's a Beatles song refrain in there as well as a few pub jokes I suspect. Oh! And am making moules and frites for a run ending tomorrow eve at Green Flash Hash>
Reading FAQ's concerning sulfur de-nitration and the answers given on these questions on WetWebMedia let me decide to ask this question: has Bob Fenner or one of his panel ever used BADESS to lower high nitrate levels or used BADESS to keep the nitrate level very low removing high daily nitrate production?
<I have not personally; have only chatted w/ others, read re>
From what I read I may conclude that this is not the case because a sulfur denitrator will not work and can not be managed satisfactory the way it is advised on your website. BADESS is very easy to manage and very reliable but only when enough sulphur is used and the reactors are big enough for the purpose they are used for. Carbon dosing makes it very unreliable and very difficult to manage.
<I do agree w/ the last>
A sulfur-denitrator must not be mixed up with a carbon de-nitrator and both reactors must be managed in a different way. BADESS makes it possible to have full control over the nitrogen cycle in an aquarium system on a very easy and practical way but not when the advise given on your website is followed.
<Do send along your corrections and we'll add>
Sincerely Yours
Belgian Anthias
De Mille CMF
<Bob Fenner>

Sulphur Denitrator   6/17/14
Hi Guys
<Hey Arun>
First of all let be congratulate you on proving a stellar website for novices as myself.
I have a relatively simple question, having recently purchased a used Korallin denitrator I set it up with the existing media having run it for about 6 weeks I still cannot detect a reduction in the main displays nitrate level.
<Mmm... Perhaps the media... might I ask you to measure the nitrate and pH of the water just exiting the reactor?>
I have decided to change the sulphur media ,

not knowing how long it has been used for, when I researched the product I came across sulphur prills used primarily by horticulturists ,it states that it is 99.5%pure sulphur, it is a fraction of the price of the packaged
products sold by the online aquarium stores.
<Ah yes>
Will this product be safe to use, and based on what I have read can you advise me whether the packaged aquarium sold sulphur is coated with the nitrate eating bacteria?
<It should be safe to use, though I might test a batch on a small experimental set-up (not on your main/display)... "just in case". And no to bacteria being applied to aquarium sulfur products as far as I'm aware/have seen>
Thank you Arun Sharma
<Welcome. Bob Fenner>
Re: Sulphur Denitrator
Thank you Bob
<Welcome Arun>

Sulphur denitrifier, use with sulphur, or bio pellets?   11/17/13
Hi Bob,
?????????? I am hoping you can help me once again. I have a 180 gal FOWLR that's been running for about 18 months. It always has high NO3, fish are well fed and healthy but I would like more control of NO3 than reduced feeding and big water changes would give me. I have tried carbon dosing for several months now without change
<Doesn't always "work"... only in/w/ systems that are carbon deficient>
in my parameters using Red sea's Nopox liquid, I read people have success
with carbon dosing sooner than this, but I have not been so fortunate. I have two skimmers running in my sump, Red sea's C-Skim 1800, and an old TurboFlotor 1000 which uses ozone, plus? Plenty of live rock so it should work. The skimmers certainly pull out plenty of skimmate.
?????????? I have an old Korallin sulphur denitrator from an old tank currently in? Storage.
<I'd get it out; try using it here>
 It was fiddly to operate and sometimes smelly, but good at reducing NO3, though I was always worried about the acidic effluent affecting alkalinity.
I am debating? If I should resurrect this denitrator? For my current tank.
The denitrator? Recirculates tank water within itself via a pump, but? has a low flow rate in and out for the anaerobic bacteria it utilizes. I was wondering if I could use bio pellets with this denitrifying filter instead of sulphur.
Would that work?
Are bio pellets preferable to sulphur denitrification??
<... depends on the make-up of the system, cause of issues... the two mechanisms mentioned are not dependent on each other... Operate independently. Sort of like asking re using a bike to get about vs. using a blender to make a drink>
Would be interested and thankful for your advice,
<?Bob Fenner>

Sulfur Reactor    6/28/13
Hi Crew!
I have a sulfur based nitrate reactor (Korallin brand) that I would like to use on my saltwater reef tank. It is extremely difficult to find useful (and well cited) articles on this subject. I read all of the FAQ's about this topic on your page, but cannot seem to find any articles about it. I do have a few questions about the process and would like better clarification. First, does the unit release a toxic sulfur compound back into the aquarium? I have read some claims that it does, and other claims that it does not.
<It does not... unless there is some gross mis-use of wrong media...>

Second, is the reactor safe to use even after the nitrates fall to an appropriate level, or should the process be discontinued until when/if there is another nitrate spike?
<It is safe to use continuously>

 Next, the ph leaving the reactor was 6.0-ish, and that is obviously very low, but I cannot seem to correct the imbalance. The instructions mentioned to have 2/3 sulfur and 1/3 calcium carbonate,
<What is the source... the brand, make-up of the CaCO3? Some types are varyingly in/soluble. You may need to have a higher ratio of carbonate... Otherwise, I'd consider running the water through a bit more quickly (let's say so the pH is 6.5 or so) and baffling/aerating the water at the discharge point to further elevate pH>
 but in an attempt to correct the low ph produced by the sulfur, I did a 50/50 mix, and the ph is still low (roughly 7.0).
<This should be fine>
 So should I use even less sulfur and more calcium carbonate, or is that defeating the whole purpose of the unit to begin with?
<Not defeating; other than diluting the Sulfur exposure per pass>
 Finally, can the calcium or alkalinity be negatively affected by this process, or will they remain more stable because of it, or is it not going to really impact the system at all?
<Both alkaline earth (Ca, Mg...) and Alkalinity can be (dangerously) reduced (via acidification)... You should be measuring all to assure these are not dipping too much, too fast>
I appreciate your time, and help with my questions, and hopefully this will help other people just trying to get the basics of sulfur denitrification and its effects on the tank parameters other than nitrates.
<Welcome. Bob Fenner>

DIY Sulfur reactor design - request schematic review?     3/2/13
Bob, at your prior suggestion to me on nitrate reduction, I now have a DIY biopellet reactor running. Seeing that I could implement a sulfur reactor using similar (cheap) materials, I have all on order and wonder if I could trouble you for a quick design review and a question
<Sure; have looked over>
I have. Also, to point out, each will be undersized (slightly) for my system, which may serve to insulate me from overly stripping nutrients from my water (?).
<Might well help>
I can't expect that to be a problem in my system of messy eaters where nitrates still hover around 20-30 after large (30-40%) water changes, but time and experimentation on throughput will tell...
Anyway, on to my design. See the attached, which hopefully is self explanatory. For my 200G system, I plan to use 1.2L sulfur and 1.8L of course aragonite media. My design deviates from common sulfur reactor practice in that there is no aragonite in the sulfur chamber (i.e., which recirculates). Effluent from this chamber drips to an aragonite chamber (fed at bottom), where it will gravity drip (out of top) to the system.
<... gravity feed? The system water will be pumped through the S2 reactor and then through the aragonite, yes?>
Now to my question. Is this amiss for not having the aragonite in the recirculation chamber?
<It is not. In fact, your design is better... for isolating the two media>
 Should I add some aragonite here, or reduce sulfur to a level where I can have a ratio of sulfur/aragonite subject to the same chamber circulation?
<I would stick w/ what you show for now>
Any other design concerns?
<Just the drive of sulfur into your system... go slow flow wise, measure the effluent pH...>
Thank you!
<Welcome. Bob Fenner>

Re: DIY Sulfur reactor design - request schematic review?    3/2/13
Bob - thanks! To answer -
<... gravity feed? The system water will be pumped through the S2 reactor and then through the aragonite, yes?>
The system water will be pumped through the S2 reactor and to the aragonite vessel (entering at bottom). The aragonite will overflow and drip into the tank (i.e., no pump within it).
<<Ah yes...>>
Should I go with this plan?
<<Looks fine. B>>

Re: DIY Sulfur reactor design - request schematic review?   7/12/13
Bob, hope all is well. Question on sulfur reactors and use of GAC within...
Is this a concern? On occasion, I have had hydrogen sulfide odors coming from my sulfur reactor. This has primarily been a result of flow tweaks, but also I have had problems with the tank water supply pump clogging (and/or inadvertent pump power shutoff).
<Mmm, well; if only "a bit" (humans have quite sensitive/acute sense of this, other S containing cpd.s), not a big deal... IF filling the house w/ the odor, an issue>
I have noticed that temporarily placing a bag of GAC within the chamber helps me get the reactor back to normal.
 Is there any concern with just running the sulfur chamber full-time with GAC present?
<There is not (as far as I'm aware of course). Have seen hobbyist to large commercial reactors w/ a chamber of GAC as a finish contactor many places/times>
<Welcome. Bob Fenner>

Adding co2 to a sulfur denitrator? -- 10/21/2009
Dear WWM
I have a sulfur denitrator which uses a Korallin 1502 shell. I was wondering if the denitrifying bacteria that live in the sulfur can live and work in a co2 enriched environment?
<Yes... often carbon is a/the rate-limiting (Amtal Rule) source material; hence folks feeding sugars, alcohols...>
The reason for injecting co2 would be to increase the calcium output of the denitrator.
<? Do you have a source of this alkaline earth element in your reactor?>
My well water even after my R.O. and polisher has a ph of 7.8 with the denitrator I can push it to 8.0 with out buffering. After that it requires buffer which drives up my ALK. The system is 240 gal with a 150 gal. refuge.
Lots of circulation in main tank. I have about 68 mixed corals, 8 fish largest about 3" in addition to a fair clean up crew. I can do this it would save adding a separate calcium reactor. Thank you.
<Mmm, if I'm following you here, you can likely improve your system overall with some careful (metered) input of carbon dioxide being fed into the reactor... I would mix some sort of CaCO3 in with the Sulphur beads. Bob Fenner>
Re: Adding co2 to a sulfur denitrator?  10/21/09
Thank you Bob
<Welcome Larry>
The sulfur denitrator I have is a new innovation designed and tested at the aquarium of France. It works exactly like the Korallin 1502 calcium reactor.
The difference is the bottom 1/3 is sulfur beads the top 2/3 a calcium media like ARM in addition there is no Co2 added.
<Ah yes, have seen this... the CO2 can be scavenged/released from the calcium carbonate/ARM... in the reductive ("acidic") circumstances in the contactor>
. There are no sugars added like many sulfur systems. I hope this clears up any confusion about what I have.
Thank you again for your help.
<These units can/do work under some circumstances. BobF>
Re: Adding co2 to a sulfur denitrator?  10/21/09

Thanks Bob
<Welcome Lar>
If I understand you right you don't feel that the addition of Co2 gas will hurt the bacteria in the sulfur bed.
<Up to a point, it should help... You don't want to add so much that the pH drops precipitously...>
I would set the Co2 gas injection system up just like a normal calcium reactor. Using a bubbler and a ph
monitoring system like the 122 with slave valve for the gas. I would start with 5- 10 bubbles/min.
<This should be fine>
I just wonder why no one has done this before!!
<I do think it has... Not likely commercially viable commercially, as the CO2 cylinder purchase/lease, regulator, needle valve, monitor... would put the cost beyond what most folks would pay. BobF>
Re: Adding co2 to a sulfur denitrator?  10/21/09

I have used this sulfur denitrator in my old 75 gal tank with a 30gal refuge.
It worked great and kept my nitrates at 0 and calcium a little high if I didn't watch it. The 75 was wall to wall corals and about 25 fish. I swear by them. It just won't provide enough calcium for my combined 400gal
<Perhaps a larger unit... or "ganging" another all CaC03 unit after the denitrator... or a better, more soluble source of carbonate (try Korallith, Knop's product...)>
I can either buy a calcium reactor or if I can get a little more out of the sulfur denitrator by adding Co2 I won't need to.
Thank you
<There are other approaches... do consider the few I've mentioned here. BobF>
Re: Adding co2 to a sulfur denitrator? -- 10/22/09

<Big L>
Thanks for the info. I just purchased a Korallin 1002 I will add it to system. Then maybe I will experiment with the Co2 in the sulfur system. It would be an interesting concept if it works.
<I do agree... and would like to relate that like A. Einstein et al.s "radical" designs for refrigeration (yes, including nuclear)... I've seen some very adventurous denitrator engineering... A few Interzoo's (Int'l industry/trade show) back, I saw a hand-blown glass menagerie from an Italian co. that fed H2SO4 (yep, Sulfuric Acid) into a carbonate source to feed such a unit... Wowzah! B>
Re: Adding co2 to a sulfur denitrator? 10/24/09

<Hi there Lar!>
It has been a pleasure talking with you. It is nice to meet someone in this field who is not entrenched in the tried and true and keeps an open mind to new innovations and ideas.
<I will state the same re my impression of you, yours. Cheers! BobF>

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.>

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 -- >

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>

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.>

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.>

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>

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

Sulphur with a carbon source... Tricky Q's re denitrators  - 10/06/2009
Hi my name is Steen... i have more then one question, but they are related, so here goes...
I read an article that you can start up the bacterial culture in a sulphur reactor much quicker by dosing vodka, and just letting it recirculate for 3 days (can't find the article again, REALLY annoying!). I can't really find the information i want anywhere, and i have posted a similar thread on a LOT of forums, no useful replies! I want to dose a carbon source and run a sulphur reactor at the same time:
1) Would it be beneficial to dose it slowly through the sulphur reactor?(diluted form dripping slowly into the reactor intake)
<IF carbon is limited...>
2) Would it work kinda like a combined carbon based reactor with a sulphur based?(i don't know enough about the differences in the cultures living in carbon based and sulphur based reactors)
<Mmm, not if I understand your question... No... the ethanol will only further chemically feed the sulphur-based bacteria>
3) What possible Long term effects could there be when combining them?(the sulphur beads getting covered with a culture living of the carbon and thereby not utilising the sulphur)
<Mmm...Combining the C2H5OH? When something becomes rate-limiting... reaction series will slow>
4) Is the RedOx the same in both types of filters?
5) What difference would there be between using VSV and vodka?
5.5) My skimmer is acting strange after i started, most of the time it does absolutely nothing, and some times it just go crazy, not like more 'dry' foam being created, just the water/foam level rising and overflowing the cup in no time!?!?
<To be expected>
Hope you can help me out with some information on the subject(s), and if not then thx 4 your time anyway :)
p.s. I actually started 3 days ago to dose 30ml vodka a day very slowly into my 18kg sulphur reactor(cleaned 3 weeks ago, so not really matured yet, trying to keep it around -170mV) for my 900l tank which also runs a reactor with 1000ml Rowaphos and a reactor with carbon and shuran150 skimmer...
<I'd reduce this to 10 ml.s maximum. Bob Fenner>
Re: sulphur with a carbon source   10/7/09

i Bob, first of all thanks for your answers :) So what i get from it is that if carbon isn't a limiting factor there'd be no advantage in dosing it trough the sulphur denitrator,
but you would limit it to 10 ml 37% vodka pr. day in a filter containing 18kg sulphur beads, why is that?
<IF there is too much Vodka added (beyond the metabolic use of the microbes in the denitrator) the excess can/will go on and have "other adventures" in a system... the lesser of which are (usually green filamentous) algal profusion. 10 ml.s is likely about the limit of good you can do here. If you had/have diagnostic tool/s for determining excess hydroxide concentration, I'd actually measure/monitor... though you will very likely find that the "use" of ethanol vacillates...>
If i dose it, still keep the ORP/RedOx potential between -100mV and -200mV.
<Too low... for the main system. Are you stating for the reactor discharge water?>
Could there be an increased risk of clogging the sulphur denitrator if dosing into it?
<Yes; slightly>
I hoped that like carbon based denitrators that use bioballs, the sulphur beads and aragonite would provide the surface area for the bacteria to grow on when dosing vodka, but that would not be the case. And using pure vodka has no advantage over VSV other then being more expensive, since sugar and vinegar are really cheap!(any drawback with VSV?)
<None that I'm aware>
Have you heard about 'quick restarting' a sulphur denitrator with a carbon source?
<I have, and discount it/this. In most any established system there is sufficient carbon in place to initiate denitrification in these units w/o supplementation. I would make an equivalent statement with the forward reactions of nitrification and presence of sufficient nitrogen compounds.>
and again thanks for the advice you've already given, and thanks for your time..Happy Landings... Steen..
<You too. BobF>
FW: sulphur with a carbon source   10/7/09

Hi the unit is behaving totally weird now, it fluctuates A LOT when power i disconnected
<!? I would NOT disconnect power here... like "the spice" (Dune/Herbert), the water must flow>
and connected, so by disconnecting it i can get any value i want, plug it back in and everything looks all right, except the aquarium ;) ... I have tested it on a solution with a known RedOx and it indicated -40mV
<Danger! You do NOT want negative ORP>
in a 300mV solution, problem is that i costs me 40 dollars to receive the package every time, because it is from outside the EU and 15 to send, so if i send it back and you repair the unit at you send it back to me, it will cost me 95 dollars in total excluding the price of the unit, don't really know what to do here, hope you can help me somehow...
<? Am not following you... What package? Media/stock feed? BobF>
FW: sulphur with a carbon source
sorry mate, was not intended for you, my RedOx unit is broken :)
<What a relief! Of life, living things in our world, we don't want negative ORP. Cheers, BobF>

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