In this Special Pet Fish Talk Show first Tom and Robert in New Jersey talk about denitrification, then Tom and Nevin talk about denitrification of aquarium water.

Click here now to hear the Special Pet Fish Talk titled "Denitrification", which is about 92-minutes long.

Shown above is the first denitrifier that Nevin built and talks about during this special show. This denitrifier takes in water at the upper left. The water flows down the 4" diameter ABS pipe, makes a U-turn at the bottom, and comes back up, then flows back into the system. Inside the pipe is denitrifying media, which in this case at this time is bio-barrels. As the water passes through this denitrifier, the bacteria first consume all the oxygen, then the bacteria must rely on nitrate, which they consume and denitrify the water, then the water flows back into the system. This denitrifier has never removed much nitrate from the water. Probably because the media does not contain enough surface area for the bacteria.

Shown above is the second denitrifier that Nevin built. It is an inexpensive 5-gallon plastic utility bucket that is filled with media that is sold and labeled for denitrification. The water flows from above into a 2" diameter piece of plastic pipe that carries the water to the bottom of the bucket. The water then flows outwards and upwards until it overflows the bucket. This simple denitrifier has reduced the nitrates in this system from over 80 ppm to about 40 ppm, which is thought to be about ideal in a system like this. So this very simple denitrifier works very well.

Here's Nevin pointing to the third denitrifier that he built. This denitrifier is again contained in a 5-gallon plastic utility bucket. The water is pumped from the system into the bottom of the bucket and flows upwards through the denitrifying media. Near the top of the bucket is a threaded plastic L-fitting that screws into the bucket and connects to a piece of clear plastic tubing that returns the water to the system. This denitrifier is now working too well and removing all the nitrates, which may force some bacteria to use sulfates and produce hydrogen sulfide. When Tom inspected the system, he noticed a smell that my be partially hydrogen sulfide. The solution may be to remove some of the denitrifying media in the bucket. Incidentally, on the left in this photo is a commercial bio-wheel filter.   Click here for more about using Lava Rocks for the Denitrification of water in aquariums and fish bowls.

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