Originally Posted by sprmankalel
How old is the tank? Sound like a cycle is going on. I would use Seachem Prime or AmmoLock to detoxify ammonia but keep it available for the cycle to complete.
I'm fairly certain it's not a cycling issue. The tank is about 4 months old, and it was started with the gravel, filter, and some of the water from one of my well-established tanks (the 10 gallon they used to live in). I'm familiar with what cycling looks like in terms of the levels fluctuating. There's no bacterial bloom after water changes, and the levels do not fluctuate erratically after water changes or increase rapidly for no apparent reason.
This is the normal and expected result of fish living, eating, and pooping in the water, only it hits 'critical mass' faster than expected. (Although maybe not "faster" for Platies...)
My concern is whether I can safely increase water changes to accommodate the 'critical mass' without negatively affecting the good bacteria in the aquarium, and if so, what would be the best way to do that (either a higher percent of water changed or just more frequent water changes).
I'm certain it's not an issue of overstocking. It's a 20 gallon tank with 6 Platies (not even fully grown-- maybe 1.5" each), one Golden Wonder Killifish (about 2.5"), and two Diamond Tetras (a little over 1" each). (Diamond Tetras are temporary; this issue existed well before they were introduced to the tank, and doesn't appear to be affected by their presence.)
I should also add that I am diligent about checking the filter, using a gravel vac when doing water changes, and cleaning the algae, etc. from the glass.
I'm unwilling to use chemicals as a) they will not solve the problem (levels will just continue to increase, not balance out eventually as with a cycling tank); and b) I don't feel they are a substitute for regular tank maintenance.