I completely agree with Glenn here. Water changes weekly, maybe ten gallons with Reef Crystals salt should keep your tank quite healthy. As bstreep as said "Saltwater is cheap." and I agree. James, I just added a CA reactor since I have put alot of SPS in there, and since I am going SPS dominant (even with a large fish load) I found that this is going to be the most managable, hands-off approach to keeping my tank. I am hoping that by next month I will have my tank situated enough to be able to keep my hands out of the water, only in to feed nori. In a tank that is not SPS dominant, just those changes should do you great.