keeping calcium

[Ruth]

Your toadstool is not absorbing your calcium. While they may use a very little bit it is doubtful. Calcium is abosorbed by calcifiying creatures such as Clams, Small Polyp Stoney corals(SPS), and to a somewhat lesser degree by Large Polyp Stoney corals (LPS). There are others but those are your big users of calcium. You need to have calcium, alk./hardness, and magnesium in balance. I try to maintain mine at close to natural sea water if I can so Calcium at 400ppm, alk/hardness at 8dkh, and magnesium at 1350-1400.