For best growth of coral or coraline you have to have the proper balance of CA
and Mag. Water flow and lighting are important as well.
Definately get that RO
unit! Having pure water as your source will help a ton in the long run. I have found doing regular PWCs (every other week) that I get maximum growth from my corals. I've also come to the point where I have to supplement my CA
becuase of the number of SPS
corals I have in my system.