I have a question in regards to bacterial denitrification. I've been in the hobby for about sixteen years, but due to a recent unavoidable circumstance that has me babysitting two five-inch pond comets in my 20H, I'm (obviously) experiencing practically uncontrollable nitrate levels for the first time in history. Heh.
Due to my devout hatred of chemicals and total lack of time (4.0 GPA = no free time), I've decided to combat this by constructing my first coil denitrator to rid myself of the elevated nitrates naturally. I had the materials laying around, and I'd been meaning to build it for a while -- this just gave me an (extreme) excuse.
The problem arises in that, now that the denitrator is connected to the system, my fish have been behaving as though there's not enough DO in the water. I have two pepper Corys and a Siamese algae eater (I hadn't been keeping much due to my lack of time) in addition to the two carp that I'm holding onto until pond repairs are completed. The Corys, who usually hang around my java fern, have been hanging around at the top, sucking air bubbles seemingly once or twice per minute. The carp are hanging around at the top as well. The Siamese algae eater has taken to resting on an anubias leaf that sits particularly close to the top, right in the path of my canister flow.
If there are any folks out there who have used bacterial denitrators before, my question is, could the denitrifying bacteria be producing sulfuric gases in such quantities as to decrease the DO level in my water? I know the obligate anaerobes produce sulfuric wastes as metabolic byproducts, but I don't know in what quantity they produce them, and if that quantity is sufficient to deplete other dissolved gases in the water body, or any other detrimental effects, for that matter.
If anyone has experience with coil denitrators, or any knowledge that would be of help, I'd greatly appreciate it.