Hydrocarbonat is a pure natural product, free of impurities for use within our Calcium reactors. Hydrocarbonat also has uses as a substrate in African cichlid systems or in bypass filters to raise the pH of Calciumreactor effluent. A natural calcium-carbonic acid equilibrium is created in all systems with an alkaline pH value. In our Calcium reactors supplied with CO2, the Hydrocarbonat is completely dissolved into calcium carbonate, becoming available for assimilation by hard, and many soft corals, sponges, echinoderms, etc. Hydrocarbonat is available in Medium grain size (3-5mm). For use in Calcium reactors, in hardening bypass filters, and as substrate in Malawi/Tanganyika exhibits. Container Size: 15 Liter, 3.9 gal. bucket.