Denitrification

[bioload]

Looking for a way to reduce the nitrate level in my tank, and a water change will dilute, but I've also seen a few de-nitrators that create anaerobic conditions for bacteria to colonize. The bacteria from what I've read will, through their respiratory process, will convert nitrate back into nitrogen that can then be released.

"2 NO3− + 10 e− + 12 H+ → N2 + 6 H2O"

In addition, I've read that a "œfood" source of carbon (sugar, vodka, etc.) or sulphur is required for the bacteria to survive. "¦"¦..or I may have misunderstood what I've read and everything I thought I knew up to this point is wrong.

This got me thinking of live rock and those that do not dose these "œfood" additives to their tank. What food source would be available for anaerobic bacteria with the rock?

 

[Randy Holmes-Farley]

Any organic matter in the aquarium can serve this purpose. Both natural seawater and reef aquaria have dissolved organics already in them, although adding extra organic matter can drive both aerobic growth and anerobic respiration, both of which can lower nitrate and the former reduces phosphate as well.

 

[bioload]

Thanks Randy,

If I understand correctly denitrification would occur successfully in anaerobic conditions containing dissolved organics, without any "additional" food source.

I was looking at the Aqua-Medic Nitrate filter seen here which uses and additional food source, stating "you can inject Denimar-Powder with a sringe to enhance denitrification", and wanted to know if this was really required?

 

[Randy Holmes-Farley]

Yes, denitrification works without additional organics added, and works even faster with additional organics added.

IMO there is no point is setting up a denitrifier without adding organics (or sulfur) into it.

But many folks find nitrate reduction by adding organics alone (vodka, vinegar, etc) without the device, works well too.

There are millions of thereads on denitrifiers and also on organic carbon addition to see folks experiences with them.

I presently use macroalgae growth, organic carbon addition (vinegar, and a little vodka), GAC, and skimming to reduce nutrients like nitrate and phosphate.

 

[caribbeanguy]

Randy is there any reason why one could not use Sulfur and still drip Vodka or would this require a modification to the Vodka dosing regiment?

 

[Randy Holmes-Farley]

I do not see a reason one could not or should not use both.

Just be sure the denitrator does not become anaerobic (H2S production) from lack of any nitrate in the water to supply oxygen to the denitrator. I do not know if the can happen with a sulfur denitrator unless the flow is very low, but you might monitor it (by smell, for example).

 

[caribbeanguy]

Thanks

 

[bioload]

Still going through those threads btw. Just finished the DSB in a bucket and will be moving onto some vodka.

Just be sure the denitrator does not become anaerobic (H2S production) from lack of any nitrate in the water to supply oxygen to the denitrator.

Just confirming.....If an anaerobic rector consumes nitrate faster than it's being produced the result would be the production of hydrogen sulfide?

How could one prevent this?......would low oxygen level in the reactor help, rather than no oxygen?

 

[tmz]

I ran a sulfur denitrator alongside vodka dosing for a couple of months when nitrates were high. As they neared/reached zero it became difficult to get the right balance of sulfur volume and effluent flow without hydrogen sulfide. I reduced the sulfur volume and increased the flow but still had the issue. Perhaps I needed to modify the reactor to allow even more flow but once the nitrates were low moderate vodka and vinegar dosing kept them that way for the last 16 months without the reactor.

 

[Randy Holmes-Farley]

Other than keeping the flow high enough, I don't see a good solution to the risk of running a denitrator to produce hydrogen sulfide.

 

[builderguy]

what about the new solid NP Pellets, etc.?

I'm thinking about using those. I've had good luck with Seachem's DeNitrate in a reactor in the past as well.

 

[josh11551]

how much vinegar should be dosed per 5 gallons?and it is standard distilled white vinegar right?

 

[Randy Holmes-Farley]

Yes, cheap white vinegar. How much depends on the tank quite a lot. I've dosed a wide range to my tank and think the dose is not critical, but I'm reluctant to recommend a dose for others. It is about 1/8 as potent as vodka.

 

[josh11551]

would it help if i actually gave some info??lol but my nitates are at around 20. just give me an idea for a dose, please.

 

[rpjaws74]

Mr Randy Holmes-FarleyI have a question maybe you can hlp me with.I have a problem with high ph and somewhat high nitrates. I tried lowering the ph by using vinegar but it seems to work temporarily because it eventually goes back up. I took the lids of my aquarium and I dont have intense lighting. Any ideas what could be causing it. And lastly how do you dose vodka for high nitrates I mean how much per gallon. And this two methods for how long can you continue to dosing with this products. Are they safe longterm or is it a quick fix? Please anybody feel free to educate

 

[tmz]

Heavy algae growth can raise ph . What is it btw?

Vinegar is a carbon source as is vodka. Vodka is 8x stronger. I've been dosing both for over 16 mos . Nitrates stay under 0.5ppm in a high bioload system.

 

[ctenophors rule]

Heavy algae growth can raise ph . What is it btw?

can the increased oxygen from algae raise the ph enough to where it would be dangerous for other tank inhabitants?

would the higher ph maybe harm the algae and cause it to stop photosynthesizing?

 

[tmz]

In a tank with p[oor air exchange it might go high enough if combined with relatively high alkalinity to cause a biotic precipitation of calcium carbonate with consequent bounces in alkalinity which could harm some sensitive corals. Otherwise , it's hard to imagine CO2 depletion significant enough to harm other photosynthetic organisms since CO2 from the air would likely equilibrate enough to prevent it. Since the OP didn't list ph,I have no way to asses it in terms of wether it's dangerously high or wether testing error might be an issue.

 

[Psionicdragon]

If you use a sulfur denitrater, it will reduce almost all the nitrate as it is introduced into the system. If you use vodka in combination, it may not do much because there is a N ratio that needs to be maintain for the bacteria to consume the nutrients. If you have no N and a lot of P, then nothing happens. P will just stay in the system until it is moved by some kind of media.

I think the pellets are easier to use compare to a sulfate denitrator. The cheaper one that I am using (Reefing Evolution) works the same as the more expensive brand (NP BioPellets).

 

[tmz]

Yes with no nitrogen P and even the extra C may not process.
However, the sulfur dentrator was useful in dropping high nitrate quickly( 80ppm to near zero in 5 weeks including cycle time) without the risk of dosing too much organic carbon compared to an often long time (months) with carbon dosing alone. Once the nitrate got near O the carbon dosing alone has held them down quite well, in my experience.