Thanks for the thoughts. I have found that if the ph gets above about 7.6 the tetras get really stressed, stop eating, and in the case of my neons they seem to stroke out and die. I was losing neons at a saddening pace until I got the ph lower. I'm sure it is a mixture of one thing plus another plus another, not just ph by itself.Flashygrrl said:You need nitrates in your tank and I think sometimes lower nitrates like that actually contribute to an algae problem, anything up to 20 is ok. Plus, you might want to stop with the chemicals, it can make a problem worse. 8 isn't horribly high for pH and most fish can adjust, plus you can try to filter over peat for a more natural solution. Sounds like the filter is helping.