Ideal for Spa Cartridges! Leslie's Cartridge Cleaner is a blend of cleaning agents and degreasers specially formulated to penetrate deeply into any reusable cartridge filter and remove the accumulated materials such as suntan lotion or oil, body oil, grease, dirt, soap scum and other organics. This thorough cleaning allows cartridges to be reused many times. Leslie's Cartridge Cleaner will not harm any filter cartridges. Dosage: Mix 4 oz. per gallon of water and soak cartridge overnight. Dosage: 4 oz per gallon