I can't keep up levels

[mattdean]

I think you are stressing too much on having the "perfect" numbers. I have a 125 gallon mixed reef. I dose 260ml of Ca EVERY DAY and can't get my levels over 400! In fact, I usually get a reading of 350. My Alk is 9, my Mg is 1350 to 1400 (still trying to balance it better), BUT.......I have about 140 SPS,LPS, zoa corals/frags/clams in my tank - everything grows like a weed in my tank and all my corals are happy and healthy. My tank is gorgeous, so I will try to up the dosage a little more, but I'm through stressing over it.

So, use your coral's health as an indicator and the numbers just as a reference/guide. If you have a lot of SPS/Clams, etc. using up calcium, you are going to have to dose more.