actually, the tank is a very neutral 7.5ish the oscars and the GTs as well as the africans have not had any problems what so ever with the levels that the tank is at... that is a common misconception with what different types of fish can handle. If you get your fish from a LFS chances are that they store all their cichlids in the same type of water conditions... all around 78 degrees, no nitrites, fairly neutral water softness/hardness, and the pH is around 7.5 that is really all these types of fish need.