Kirkwood;729538 wrote: It doesn't make sense that if you were doing water changes and you had no coral, that you would not eventually have coraline growth. There is nothing in your tank that would be depleting your calcium levels. What kind of salt are you using? Perhaps the salt you are using has deficient alk, calcium, mag levels to start with. If you have to dose calcium when you are just beginning to add coral, that is a problem that will only magnify itself as you add more coral and it grows out. Additionaly I would look for optimal levels around kH 8.5, calcium of 450, and magnesium at 1350.