Ok, I have a 40 gallon. Rocks driftwood and several live plants. I've been doing a fishless cycle. Everything was going fine. Now my ammo is almost none but not quite, my nitrites are zero and my nitrates are sky high! Which is a good sign. Should I continue to dose ammo and check to see if it will go to zero in 24 hrs? Or do I do the big water change? Also my PH dropped from 7.6 and higher to around 6.0! Any suggestions on boosting it to a neutral level?