ammonia sources / aquarium chemistry
 

SO i have a couple questions about where and how different sources can affect aquarium chemistry.

first, I had ammonia/nitrite posioning kill off all my tiger barbs and cory cats in my 110g. Initial testing showed increased ammonia (about 1-1.5ppm depending on when the last change was) and an increase in nitrite (.25ppm). I now believe the initial spike was caused by an antibacterial air freshener, however its been several weeks and im still doing small water changes every other day to keep the ammonia and nitrite levels down, and even doing so many water changes my nitrate stays about 40ppm.

While cleaning out one of my filters today I found a brown glob i suspect at one time may have been the last of my tiger barbs that disappeared. Could a source of ammonia such as a decomposing fish that couldnt be eaten cause not only a spike in ammonia but also a spike in nitrite/nitrate?

what different sources (gravel is vaccumed frequently) could cause a spike in all 3 readings? Ph has maintained a steady 7.4 or so, and I find it hard to believe after over a month of very frequent water changes the antibacterial agents could still be effecting the water, if they ever did in the first place.

your nitrates are way too high at 40 ppm as well. how long has the tank been established? was it ever cycled? there are lots of things that can contribute to high ammonia/nitrite/nitrate levels in your tank, but the most common is that the tank was never cycled. so we will need to know that.

the tank was running perfectly for quite some time, id say a little less than a year, and it had cycled just fine.

im not sure if my barbs/cories got sick which led to them dying or if something got into the tank that killed them (i.e. air freshener) and the dead fish caused all the spikes, but thats the long and short of it.

the high nitrates shocked me actually, ive only seen nitrates that high on an unplanted tank with a koi in it that gets water changes once a month, sometimes every other month :O

id think your air freshener even it was antibacterial was very unlikely to be the culprit. but a few questions. was it used in the same room as any other tanks. because it would have more likely affected smaller tanks much more harshly as they would have less bacteria. i think your brown glob did it or maybe a water change w/ unconditioned tap water? i really have no idea but it would have to be a pretty universal killer of bacteria. maybe a really tough bacteria infested your tank and ate all your good bacteria? are all the fish in your 110 deceased?

Re: ammonia sources / aquarium chemistry
 

Any increased pollution caused e.g. by rotting fish. What happens if ammonia levels increase? Well, ammonia-feeding bacteria colonies grow, but not fast enough to keep the levels at 0. Nitrite-feeding bacteria populations grow much slower than the ammonia feeders, and that's where the .25 come from (notice that the increase is much smaller than the ammonia - the .25 nitrite reflects the increase in ammonia feeders). Nitrate builds up over time, so no miracle here either.

I would, btw, do one or two big water changes rather than many small ones.