DIY Denitrator Idea

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Desdinova

Feeder Fish
MFK Member
Oct 1, 2010
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Kentucky
First of all, I want to mention the fact than anaerobic bacteria process nitrates to nitrogen gas, which I believe to be non-toxic.

See Also: this link. I'm not sure about some of their info. I thought it went Ammonia -> Nitrite -> Nitrate -> Nitrous Oxide, but they seem to say slightly otherwise.

Anyway, I got a 5 gallon bucket of Pond Matrix recently. It only cost me about $110 with Amazon Prime, so I figured I would try it. It already claims to remove nitrates, but I'm thinking about helping it out a bit. I have a Magnum 350 and some spare PVC tubing; 1-1/2" or so, I think.

The idea is to string the tubing together to form a long and slim tube, which all the water must pass through, in order to get back to the tank. At some point, the oxygen is going to run out and it's going to be Anaerobic City! After that, I just have to neglect a tank for a while, until the nitrates go off the chart, and then move the denitrator over to it. I want the pipes to be at least 10 feet long; maybe 20 feet. I'll just keep snaking them around.

Thoughts?
 
Just a follow-up...

I'm less interested in this idea now, due to some recent reading. The argument was made that nitrogen gas can dissolve back into the water and recreate nitrites and nitrates. This design may be workable, but a method that includes more open air and utilizes newer kinds of bio media seems like a better approach. So, I'm basically saying that a coil filter is a bit dated. It's been done before, but probably shouldn't be done again.

Link.
 
I have seen some denitrators like the one you describe work very well. I think your approach would need some polishing though.

1.5" x 10' isn't going to create the anaerobic condition you are looking for. Bacteria lives on surfaces... any free floating bacteria will simply be washed through. Not enough of the tank water is going to come into contact with the inner surface of the pipe to be processed by the aerobic bacteria.

Consider stuffing your pipe full of pot scrubbers increasing the surface area many times and creating a lot of internal turbulence.

Denitrators don't spontaneously start working. They are a balancing act of flow, nitrate levels, surface area etc. Build your denitrator and put it on a tank. Monitor the input nitrate levels vs the output nitrate levels and slowly tweak the flow rate. As the nitrate levels in the tank change so will the productivity of your denitrator... it is all about finding the right balance over a several month period.
 
also it can take several more weeks to colonize a nitrate filter compared to cycling a regular tank filter.
 
Creating a completely anaerobic denitrator is going to be really dangerous. You have to measure DOCs and get them right on the money otherwise you end up with either (A) hydrogen sulfide gas, or (B) ammonia/nitrites. Kmuda over on oscarfish.com is a great guy and made a fantastic SAFE denitrator that, last I checked, was keeping his oscar tank down at close to 0ppm nitrates. He's definitely the guy to talk to, and knows everything there is to know about water chemistry (it's kind of scary actually).
 
Well, I did some research, starting with Kmuda. I saw some discussions regarding Pond Matrix, of which I have a 20L bucket. He basically made the case that this particular product significantly reduced his nitrate levels, through lots of testing. He was using canister filters, which is not exactly what I have in mind.

I sent an e-mail to SeaChem, asking about the denitrification process regarding this product. They assured me that it does not produce harmful byproducts in the water or into the air.

The question in my mind now is regarding whether or not there is some amount of this stuff that I could use that would keep the toxins at 0, including nitrates. I believe the recommended amount is 500ml per 50 gallons of water. What if I got a gamma lid for that 20L bucket and a few uniseals... and used all 20L of Pond Matrix for a 75 gallon tank? And if that works, then it is logical that I could string together a few buckets to handle much larger volumes. Although, one of those massive tupperware bins might be better than a string of bucks, if I can seal them properly...

Anyways, thanks for all the info! I think I'm getting somewhere :)
 
I guess that I should also mention that, in my first post, I intended to say that I was going to load up the PVC with Pond Matrix. I tried that with some 3/4" tubing that I have, but it was too hard to get it in there. The tubing is rigid. I think I would need to get some more pipe.

On the other hand, I might not need to go through all that complexity, given my recent findings. I'm thinking a big bucket/bin of Pond Matrix... and maybe a bucket of ceramic rings, placed before the Matrix. Kmuda seems convinced that the rings have much more surface area. Thus, let them convert to nitrates and let the Matrix take over from there. But maybe the Matrix is all I really need. Neo gunna to solve all my problems, I just know it!
 
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