Gail once your tank has cycled the levels you are looking to achieve are: Ammonia levels should be 0 ppm Nitrates should be kept below 10 ppm in freshwater aquariums. Nitrites should be undetectable at all times. PH in the range of 6.5 – 7.5 is suitable for most species. However as Kazza has said these will fluctuate until the tank settles and the good bacteria has built up. You should only be thinking of removing some water once (at the very most) twice a week.