DurasticksTM are your answer to the hassles of daily chlorination. This simple stick is safe on plumbing, so it can be added right into the skimmer basket or chlorinator, making daily chlorination a thing of the past. Each 8 oz. stick will treat 10,000 gallons hassle free for up to one whole week. DurasticksTM are the strongest stick form chlorine available. 89% available Triclo-s-triazinetrione. Not a dangerous and hazardous calcium-based chlorine!