I top off with RO/DI h2o weekly, then do a 10 gallon h2o change. I add Kent's Turbo calcium and Super dKH buffer to my new salt h2o before adding to tank. It's a 210 g
display, with a 45 gallon sump. I have just zoo's, mushrooms, candy cane, starburst,
sponges, and gorgorian in there now, - in April, after 7 months of opperation will add move corals.