TURBO CALCIUM provides bio-available calcium for lush growth of purple, pink and green calcareous algaes, snails, hard tube worms and clams. Corals will open more and stay attached to their skeletons better, with regular use. Phosphate & nitrate free! Contains no gluconates, EDTA, or other organics to raise DOC levels, as many competing products do. This product is the main ingredient in other calcium supplements in economical dry form! TURBO CALCIUM alone can provide all the calcium your reef will need.