Product Short Description: Sodium Thiosulfate used as a Pond / Aquarium Dechlorinator. This product also used as a Photography as a fixing agent (hypo) to dissolve unchanged silver salts from exposed negatives. Product Description: Sodium Thiosulfate commonly used in Dechlorination of municipal wastewater, pulp & paper, power, and textile water treatment plants and as an Oxygen scavenger in oil well drilling process in Mining industries. Also chemically suitable for Aluminium cation reaction. Sodium Thiosulfate used as a Pond / Aquarium Dechlorinator. But Sodium Thiosulfate does not treat for Chloramine, only Chlorine. Chloramine is a chemical compound composed of chlorine and ammonia and more and more utilities are converting to its use. Check with your municipal water company to learn which chemical they are using. If Chloramine is the disinfectant, please research other knowledgeable sources to learn your best solution for water treatment. Molecular Formula ::: Na2S2O3 - 5H2O This product also used as a Photography as a fixing agent (hypo) to dissolve unchanged silver salts from exposed negatives.