Ultima phosFIGHT Plus is a 3-in-1 formula that removes more phosphates per quart than any other product. It’s concentrated formula removes more than 13,000 ppb of phosphates in 10,000 gallons of water, it also contains a clarifier for keeping your water sparkling clean!. Add 2 oz. of product directly into the skimmer with the filter running. May be used for initial high phosphate levels; 1 oz. removes 410 ppb per 10,000 gallons.