Don't know yet, that's why I asked you about the calcium reactor :). Actually, I only have 3 more SPS frags coming in Friday, then I'm done for a loooooong time. I tested my calcium last night, it was at 450. I'm going to start testing it regularly to see how quickly the corals consume it. Then I'll decide if I can get by just with water changes and dosing, or if I need a calcium reactor.