Hmm that would depend on whcih calcium you where using , people may frown on this BUT heres what i do with 100% success, i buy reef advantage calcium, i add two teaspoons to a glass of ro water, sir it up and let it settle till the water looks normal again. Then i dump into the tank. I do this once a week, and my corals are growing like ive never seen any ones corals grow b4.