I'm with PerfectDark, you should be sure that your salt mix can't just cover the calcium levels you need. I keep calcium between 440 and 480 just through water changes since my salt mix (Red Sea Coral Pro) is rated to 460 calcium at 1.026 SG (35ppt salinity). That means as long as I keep a steady salinity, and do regular water changes, I don't have to dose. It also helps to have a buffering substrate, like aragonite. That will (very slowly) break down to add calcium to your water, since the aragonite is actually mostly made up of calcium carbonate. That helps buffer pH and alkalinity as well.
BTW, I keep a bunch of zoas and shrooms, frogspawn and candy canes, and monti-caps in my DT.