dKH: 22.4 Ca: 300 Mg: 290 pH: 8.4 Dude, the numbers are really off. Are your corals doing OK? I like to see my numbers at dKH: 10-12 Ca: 450 Mg: 1400 pH: 8.2-8.4 The reason your Ca isn't staying up is that your other numbers are sooooo off. I will have to wait for others to chime in. I have no idea what to do with this. I will keep an eye on the thread, as I am intensely curious.