Prodibio Calci Reef+ Water Conditioner for Aquariums is a hydrogel that maintains optimum levels of calcium, magnesium, and part of alkalinity in reef aquariums. A Large number of marine organisms, such as corals and coralline calcifying algae, use calcium and carbonates to synthesize their rigid structures. Releases, under the action of BioDigest’s bacteria, hydrogen carbonate ions from the biotransformation of the acetate in the calcium hydrogel and is gluconate free.