No reactor on my tank either. You need to maintain proper calcium and alkalinity for good growth, but you can do that through your weekly water changes. Calcium reactors aren't necessary, but if you fill a tank full of SPS corals you might want to consider a salt mix with higher values of calcium, alk, and mag. I liked Kent and Red Sea Pro when I wanted to increase the levels. If that isn't enough, you can dose your tank to increase these levels. Bulkreefsupply carries everything you'd need for this without the high cost of a calcium reactor.