Pool filters accumulate oils, dirt and algae over time. Regular filter cleaner works to remove most buildup from pool filters, but a soak in muriatic acid will remove tough debris and algae. Always clean your filter before soaking, as any oil present on the filter will react with the acid and ruin it permanently.
Turn off the pool filter and remove the cartridge from its housing. Rinse it thoroughly with a hose, getting between each pleat.
Spray filter cleaner all over the filter and allow it to sit for one hour or overnight. Ensure the filter is completely saturated at all times. Scrub it with an old toothbrush, removing every bit of debris. Rinse it thoroughly with the hose.
Put on the safety glasses and gloves. Add 1-part muriatic acid to 20 parts water. Submerge the filter and wait for the bubbling to stop. This may take a few minutes.
Remove the filter and rinse it thoroughly with the hose. Allow the filter to air dry and replace it in its housing.