With up to 20 uses from a single 1ltr bottle, the Clearwater Filter Cartridge Cleaner has been created to help you prolong the life of your hot tub's or pool's filter cartridges by removing oils and greases. Making sure your filter cartridge is fully immersed in an appropriate container, simply add just 50ml to every 1 litre of water. Leave the cartridge to soak for at least 8 hours for optimum cleaning performance. Once the cartridge has been appropriately soaked, rinse the filter with fresh water and allow to dry before re-installing.