Vanish will immediately remove chlorine, chloramine, and heavy metals that are often present in city water supplies. Vanish will also add a slime coat protectant to the water to help fish heal wounds and abrasions and protect them in times of stress (during water changes & clean outs). Vanish is safe for use with fish, plants, birds or domestic animals that drink from the pond. 16-oz. treats 9,600 gallons!