Once the tank is cycled you should have the following parameters:
Ammonia: 0
Nitrite: 0
Nitrate: 0
PH: 8.0 - 8.5 (stability is the issue)
Phosphates: 0
Specific Gravity: 1.023 to 1.026 (stability is the issue)
Fish only tanks can tolerate up to 40 nitrate, but you will have algae problems.
Invert tanks can tolerate up to 10 nitrate, but again, you might have algae problems.
If you have corals or inverts you want calcium around 400ppm.
I forget what the alkalinity should be.