I have been unable to keep my Calc high enough, thru dosing, in the last few days. I decided to test Mg today because I knew something wasn’t right. Wow, Mg was down to 1080. It’s normally 1420-1480. I maintained it through WC’s. At this point, what should I do?? Do back to back water changes or dose? I do not even know what chemical to dose. I currently dose soda ash for alk and calcium chloride. BRS has 2 choices.... Magnesium Chloride and Magnesium Sulfate. Please help me out....