I want to know what you're using. I have a Red Sea master kit for Mg, kH and Ca and I'm not convinced that the readings are correct.I tested all 3 tanks at home and got the same for Ca for all 3 tanks. I know this can't be right, I have 4 lps, 1 sps and 8 leathers in the 57 and there has to be a higher Ca use in there. I'm going to be looking for a new kit so I want to hear what you have to say. I value word of mouth and experience over manufacturer hype.