It all depends on the type of media you are using and your drip rate, and the efficiency of your Ca reactor. But generally speaking 6.5 is typical of a Ca reactor. You have to test your effluent for Alk. Saturated SW will only hold 32 dKH. But it all depends on how much of a load you have on your tank and the size of your Ca reactor. You increase both the drip rate and BPM to put more Ca into your system. You always want the effluent to be saturated though. It makes no sense to have a very high drip rate and low BPM, which will lead to a low saturation level. All Ca reactors are trial by error as far as dialing in, and there is no single magical formula for a set bubbles per minute, and effluent drips per minute...too many variables.