Sodium Thiosulfate, Anhydrous
Sodium Thiosulfate can be used to dechlorinate tap water including lowering chlorine levels for use in aquariums, swimming pools, and spas (e.g., following superchlorination) and within water treatment plants to treat settled backwash water prior to release into rivers.
Thiosulfate reduces the hypochlorite (active ingredient in bleach) and in so doing becomes oxidized to sulfate. The complete reaction is:
Similarly, sodium thiosulfate reacts with bromine, removing the free bromine from solution.
Sold in a granular form.