GLB Filter Fresh is an acid-based liquid cartridge filter cleaner. This product removes scale, rust, cosmetics, oil, and other materials from filter cartridges by using an overnight soak-and-rinse formula. Eliminating contaminants helps the filter operate at maximum efficiency. This product is highly concentrated and removes debris from cartridge filters. Filter Fresh may be used with chlorine, bromine, ozone, and biguanide sanitizers.