This concentrated granular is specially formulated to protect pool surfaces from minerals in the water and is ideal for use with hard water. It is also great for pool openings or when adding make-up water. (Normal Water): 10 oz per 10,000 gallons of water. Initial Treatment (Hard Water or Metals): 20 oz per 10,000 gallons of water. After initial dosage, add 2 oz. per 10,000 gallons once a week during the pool season. Sizes available: 2 or 20 lb. pails