Filter Media (usually a cartidge element) should be chemically cleaned regularly. Immerse has been designed to remove the grease and oils. This convenient 2 x 50g sachet is the ideal product to clean filter cartidges. Add Immerse to a filter cleaning bucket containing clean water and stir well. Hose the filter carytridge to remove loose debris, and then soak in the cleaning solution for at least 8 hours. After soaking the filter cartridge rinse thoroughly with fresh water and if possible allow to dry before returning it to the spa.