Hello. I’m having an issue with calcium levels. I’ve been using the MODERN REEF proportional dosing system for four months now on a 220-gallon tank. My parameters are: Alk 7.7, Ca 500, and Mg 1410. I can't seem to lower the calcium; even after turning off the calcium dosing, it stays in the 490–500 range. I perform weekly water changes of 10–15%. I use MODERN REEF salt and maintain a salinity of 35 (measured with a Tropic Marin tester). I use RO water (7-stage BRS system) with a TDS of 0. I’m at a loss as to what to do. Over the last two weeks, I’ve lost three SPS corals (they bleached).
