Bio-Dex PAO32 Super Concentrated Protect-All Supreme 1 QuartThe Bio-Dex PAO32 Super Concentrated Protect-All Supreme 1 Quart is your answer in safely removing and preventing stains including calcium and scale-buildup on pools and spas. This is a non-hazardous product with viewable results within 48 hours. A one-quart bottle is recommended as an initial dose per 20,000 gallons of water which may reduce chlorine levels but can also be remedied by a floater with chlorine tablets to rais the appropriate level of chlorine. It can already remove calcium and scale within 48 hours but a second application can be done especially with heavy scale buildup. This item comes in a 32-ounce or 1-quart bottle. Care should be considered when using this product by using your own goggles to protect your eyes and gloves to protect your hands from unnecessary incidents.