As I understand it, the nitrifying bacteria that we need in our filters becomes less efficient or starts to die off when the pH drops too low. What I want to know is, is this always the case and if so, how low is too low? My new set up (the 60 litre) is still cycling at the moment and the pH is getting very low indeed. Will the tank cycle with a low pH, and will it stay cycled? I want to keep softwater fish so I'm happy for the pH to be low and I didn't really want to have to buffer unless it became absolutely necessary, but is it going to cause problems?