I'm finding the answer to be NO for me. I have about 20 small SPS frags in my 125 and drip limewater 24/7 for topoff. I have been using Dr. Farley's 2 part recipe for only a couple of days now, as my Alk and Ca were getting a bit low. I use BioSea Marine salt which measures about 440 Ca upon making a fresh batch, so I know it's getting used up. I will be making the switch to Marine Environment salt after my next water change. A calcium reactor would be great, but it's just not in the budget right now (and won't be for the forseeable future), so I have to do this on a budget.