Kalkwasser mix provides bio-available calcium for lush growth of purple, pink and green calcareous algae, 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 original european method that has never been equaled for calcium addition to a reef system! It will provide long term results that no other supplement will! It requires a little more work, but so does anything that is really worthwhile! Kalkwasser mix can be used with kent marine concentrated liquid calcium or turbo calcium for maximum results.