Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Ditto: I would get the tank back to 20 ppm NO3, then not dose NO3 for a week, and see what happens. Here are the possibilities:
a) NO3 drops through the week = plants are using more N than the fish food is adding, so begin dosing KNO3 (but maybe half or a third of what you were doing before).
b) NO3 stays stable through the week = plants are using just about what the fish food is adding. When you do a big water change it will drop, though, so maybe you will need to dose a very low level of KNO3 though the week.
c) NO3 continues rising, even if you are not dosing.
1) Rises, but not too much. Corrected with 50% once a week water changes. This is just about perfect. Do not dose any KNO3.
2) Rises more than the 50% water changes can handle. Too many fish, too much food, not enough water changes. I would separate out all the smaller fish, if you want to keep aggressive Jewels and Firemouths in this tank. Put the Tetras, Rams and so on in a different tank.
Of course, monitor the ammonia, but I also think it was the recent deaths (especially a large fish like the FM), and the water change will probably have taken care of it.
Alternate idea: I have seen a lot of posts recently about malfunctioning tests. Whether it is an actual problem with the test kit, a user error, or some other problem, quite a few people are asking about positive ammonia tests that turn out to be something else.
Calibrate the test kits to be sure that the results you are seeing really reflect something going on in the tank.
I have seen this, too. Just a trace of green instead of pure yellow in the API ammonia test. I suspect I am testing too soon after a water change. The ammonia is from the tap water (Chloramine) and the dechlor (Prime or Chloramine Buster) is dealing with it, but it still shows up in the test.