Hey Beakerbob, I know you're one that'll know the solution and maybe a cause to this. I have a 24g cube, using Seachem Reef Salt. I do 20% water changes weekly, because of this I haven't been test my water in 2010 because the tank has been doing great. The tank is made up of macro algae, monti's and birdnest. I've been testing my water for a few weeks now. Here's today's, pH 7.8, dKH 10, Ca 500, Mg 1350, and water at 1.026, temp 79-81. The only thing I'm adding is carbonate, calcium isn't affected at all and stays at 500. I'd like to get my pH in the 8.1-8.3 range. Corals are growing great. Any ideas why my Ca stays up so high?