Sodium thiosulfate instantaneously removes chlorine.
However, some commercial preparations give incorrect dosage calculations for its use. Following these directions can result in large residual concentrations of Sodium thiosulfate over time that can approach toxic levels to your fish. Additionally large residual concentrations of Sodium thiosulfate can interfere with Potassium permanganate and other treatments. You don't even need to know how many gallons you add. We sell a device that connects to your hose, with a siphon attachment that drops into another container.