Anybody using a denitrator apparatus?

[john2gs]

UP to now, I read that there are some debates whether massive water change will reduce nitrates OR not.

other people use a de-nitrator apparatus to reduce nitrates in their fish tanks:

This is a link, on how to "DIY" a denitrator apparatus:

http://www.arofanatics.com/members/vetduck/diydenitrator/



here are other links that explains more on how denitrator works:

http://www.arofanatics.com/forums/showthread.php?t=156188&highlight=denitrator

http://www.arofanatics.com/forums/showthread.php?t=171868&highlight=denitrator

[nacra99]

Seems like an interesting idea. I'm not sure if there are commerically availible units out there, but i see a couple of issues with the DIY system shown. It's gonna be lenghty, but please give me your indulgence. Will any Chemists care to verify my observations? (It's been awhile since i've been in the lab)

1) Toxic Intermediates
Chemically, de-nitrification is the reduction of nitrAtes to Nitrogen gas. It will work fine only if the de-nitrtrification process is fully complete. Otherwise, it will give you products which are toxic to fish... Let me explain.

Under aneorobic conditions, the Oxygen atom is sequentially removed (reduced) from the nitrate (NO3-) to finally form harmless nitrogen gas (N2). As in turning ammonia to nitrAtes, turning nitrAtes to N2 consists of several steps.

The steps are Nitrate > NitrIte (NO2-) > Nitric Oxide (NO) >Nitrous Oxide (N2O) > N2.

You can already see that 2 of the intermediates are highly undesireable by themselves.
1)NitrIte is what you are trying to get rid of by forming NitrAtes in the first place. And is said to be more toxic to fish compared to the same conc. of nitrAtes.
2) Nitrous Oxide is laughing gas and a sedative (your fish will be very happy)

Also, due to the anerobic conditions which are highly reducing, NitrIte may be actually be reduced back to Ammonia!!
NitrIte > Hydroxylamine > Ammonia

So unless you can be sure that the de-nitrification can be conducted to completion, it may actually give you toxic stuff.

2) Ensuring an Anarobic enviroment
This is a pretty minor issue as compared to the rest. The moment the bacteria is exposed to oxygen.. it is instant death for them. The key is to have a long anerobic area for the bacteria to grow. The thing is we don't really know how long is long enough. You might end up with lots and lots and lots of airline tubing.

3) Growing the bacteria
If memory serves me correctly, de-nitrifying bacteria should be heterotrophic. Which means that it needs to get carbon from some form of organic molecules such as sugars or starches. To be able to maintain a healthy colony of bacteria , you're gonna need a good amount of organic material which must be injected into all that airline tubing to "feed" the bacteria. And if you want good colony growth, you're gonna have to do some form of constant injection. It is not known if there is enough suitable organic material naturally occuring in the aquarium to support such bacteria in a long run.

4) Maintainance
We all know how much gunk and bacteria sheets (the whitish or brown slime you find in your filters) form in our filters. Imagine that stuff forming in airline tubing... all 30ft of it. You might actually find yourself replacing airline tubing pretty often.
Also, i know that the design calls for a chamber of bio-balls. The moment you open the chamber to clean out the bio balls, the denitrifying bacteria will come into contact with oxygen and die. This means that you are going to have to start "priming" (similar to cycling) the entire system with sugar and stuff from scratch in order to build up the bacteria again.


I think that the DIY Denitrification system has great potential to be the next cutting edge invention of the aquarium world. But for now, it just seems like there's a whole lot of stuff to consider before we know that it will work properly. Perhaps commerical units have already solved the problems? But until then... it feel that is far simpler to do my waterchanges...:D.

cheers
Marc

[Alight]

There are commercially available denitrators that really do work. However, for Discus, I wouldn't use them, unless your water supply happens to contain high levels of nitrates.

You see, nitrate is really not all that toxic for any fish, including Discus.

When nitrates rise in a tank, a number of other dissolved organic compounds are also rising, even though the normal test kits don't measure them.

As these compounds rise, bacteria feed on them. It is this combination of bacteria and DOCs that are really toxic to Discus. These are all removed by water changes.

Nitrates are a good measure of the buildup of these materials, so it's good to use a nitrate test kit and keep the nitrates low. However, simply removing nitrates only removes part of the problem. Water changes remove all of the problem.