I've recently read on the forum here that a ph below 6.5 will kill benefical bacteria in the filter, I was wondernig if this was true? I do not see how this can be true b/c discus buffers drop the ph to about 5 respectively and I've seen that other people will inject CO2 and have a ph below 6.5. My tapwater has a ph of about 7(maybe a lil lower) with a GH and KH of 3. My current set up I buffer the water to maintain a ph of 6.7 with 30ppm of CO2. I'm getting a new tank and do not want to buffer the water any more to avoid fluctuation of CO2 because of water changes. Normally ph has to drop a full degree to have acceptable CO2, if I inject CO2 into the new tank unbuffered it will put the ph I'm guessing right now somewhere in the range 5.8ish. Is this going to be a problem with bacteria in the filters doing its job?