Dechlorinator

A dechlorinator is a chemical additive that removes chlorine or chloramine from water. Where tap water is chlorinated, it should generally be dechlorinated before use in an aquarium, since chlorine can harm marine life in the same way it kills microorganisms. Chemicals that serve this function are antioxidants or reducing agents. See redox for more information on chemistry, and Aquarium for more on conditioning aquarium water.

Some commercial pond dechlorinators are: sodium thiosulfate, Sodium hydroxymethanesulphonate (called AmQuel), and Sodium hydroxymethane sulfinic acid (called Bio-safe)