Formulated specially for use in reef aquariums, Reef Crystals contains essential ocean reef elements in concentrations greater than those found in natural sea water: - Extra Calcium to help ensure the growth of large and small polyp stony corals as well as coralline algae; - Extra Trace Elements to provide an additional measure of vital nutrients; - Extra Vitamins to ensure vigorous growth and survival of corals, anemones and other invertebrates in a captive environment; - Metal Detoxifier - to neutralize traces of heavy metal often present in domestic water supplies.