A pH of 6.4 is perfect for most all community fish - tetras, angels, corys, gouaramis, guppies, rasboras, loaches, etc. If it is stable, I wouldn't do anything to it at all. Your normal weekly water changes will raise it back up slightly everytime so it should drop much lower than the 6.4 The KH is really only a factor is you are doing something like adding driftwood or CO2 injection that affects the pH. The buffering capacity (KH) keeps it more stable and reduces the risk of sudden swings.fishwatcher said:
