Hot Tub Things Spa Cartridge Cleaner 32 Ounce - Designed for Removal of Oils, Grease and Soaps Use Cartridge Cleaner for a deep clean that keeps your filter operating in peak condition; specifically for removal of oils, grease and soaps! America's #1 Trusted Brand of Hot Tub Chemicals Safety Tested to Assure Quality, Guaranteed Performance Formulated Exclusively for Hot Tubs And Made from the Purest Chemicals Available Compare to Leisure Time Filter Clean Remove cartridge from filter housing Use full strength on cartridge and brush clean, or soak cartridge in a solution of 1 part Cartridge Cleaner to 10 parts water (1 quart to 2.5 gallons). Soak for at least 3 hours or leave overnight. Rinse with maximum water pressure. Reinsert cartridge to filter housing.