Key takeaway: Clean a pool cartridge filter by hosing it down between the pleats, soaking it in a filter degreaser for 12 to 24 hours to shift oils and sunscreen, then rinsing again. Clean it when filter pressure rises 8 to 10 psi above its just-cleaned baseline, not on a fixed weekly schedule, and expect to replace the cartridge itself every 1 to 3 years depending on how hard your pool works it.
To clean a pool cartridge filter, remove it from the housing, hose it down thoroughly between every pleat, then soak it in a diluted filter degreaser for 12 to 24 hours to break down body oils, sunscreen and algae residue that a hose alone can’t touch, and rinse it clean again before refitting. A plain rinse handles loose dirt but does nothing for the greasy film that builds up on cartridge pleats over a season, which is why pressure keeps climbing even after a quick hose-down.
What You’ll Need
- A garden hose with a firm jet nozzle
- A dedicated pool filter cartridge degreaser (a TSP-based cleaner works well for oils and sunscreen)
- A bucket or container large enough to fully submerge the cartridge
- Chemical-resistant gloves and eye protection
- A spare cartridge, if you have one, so your pump isn’t out of action while the first soaks
How to Clean a Pool Cartridge Filter
- Switch off the pump and relieve pressure. Turn off the pump at the switchboard before opening the filter housing, and release the air relief valve to depressurise the system first.
- Remove the cartridge. Lift it out carefully to avoid tearing the pleated material.
- Hose it down between every pleat. Work from top to bottom, holding the nozzle at an angle into each pleat rather than straight on, so trapped debris actually gets flushed out instead of pushed deeper in. Keep going until the runoff looks mostly clear.
- Soak in a degreaser solution. Mix a pool filter degreaser per the product’s dilution instructions and fully submerge the cartridge for 12 to 24 hours. This is the step that actually shifts the oily film a hose can’t remove.
- Rinse again thoroughly. Hose the cartridge down once more after soaking, working between the pleats the same way as step 3, until no more degreaser residue or foam rinses out.
- Reassemble and repressurise gradually. Refit the cartridge, close the housing, and turn the pump back on slowly, checking for leaks around the housing seal before leaving it running.
When You Also Need a Muriatic Acid Soak
If your cartridge has visible white or grey mineral scale, usually from calcium build-up, that a degreaser soak doesn’t shift, a brief acid soak can help, but only after degreasing, since acid dissolves mineral scale, not oils. Dilute muriatic acid at roughly 1 part acid to 20 parts water in a plastic bucket, always adding acid to water and never the reverse, and soak the cartridge for no more than 10 to 15 minutes; leaving it longer risks damaging the filter material itself. Rinse thoroughly afterwards. Muriatic acid is classified as a hazardous, corrosive chemical under SafeWork Australia and ADG Code criteria: work outdoors or in a well-ventilated area, wear gloves and eye protection, and for any exposure call the Australian Poisons Information Centre on 13 11 26, available 24 hours a day from anywhere in Australia.
When to Clean It (Go by Pressure, Not a Calendar)
The reliable trigger is filter pressure, not a fixed weekly or monthly schedule. Right after you clean the filter, note the pressure gauge reading with the pump running normally, this is your clean baseline, and it’s worth writing it on a piece of tape stuck to the filter housing so you don’t have to remember it. Clean the cartridge again once pressure climbs 8 to 10 psi above that baseline. As a rough guide this tends to land somewhere between every 2 to 6 weeks in swimming season, more often after heavy leaf drop, a pool party, or if the water’s gone cloudy or green.
Common Mistakes
- Rinsing only, without ever degreasing, so pressure keeps creeping up season after season
- Cleaning on a fixed calendar schedule instead of watching the pressure rise above your clean baseline
- Soaking in muriatic acid for too long, which can damage the pleated filter material
- Pouring water into acid instead of acid into water when diluting
- Using a straight, close-range hose jet that punches holes in the pleats instead of an angled spray between them
When to Replace Instead of Clean
A cartridge that’s cleaned regularly typically lasts 1 to 3 years, less for a heavily used pool, more for one used only occasionally. If the pleats look permanently grey or torn, if pressure climbs back to your “needs cleaning” mark within days of a proper clean, or if a section has visibly collapsed or split, that’s a sign the cartridge itself is worn out rather than just dirty, and no amount of degreaser or acid soaking will bring it back.
Frequently Asked Questions
How do I clean a pool cartridge filter?
Hose it down thoroughly between every pleat, soak it in a diluted filter degreaser for 12 to 24 hours to remove oils and sunscreen residue, then rinse it clean again before refitting. A hose alone removes loose dirt but not the greasy film that builds up over a season.
How often should I clean my pool cartridge filter?
When filter pressure rises 8 to 10 psi above the reading you get right after a clean, rather than on a fixed schedule. In swimming season that often works out to roughly every 2 to 6 weeks, more often after heavy debris or a cloudy pool.
Can I clean a pool cartridge filter with just a hose?
A hose removes loose surface dirt but doesn’t shift the oily film from sunscreen, body oils and algae residue that builds up in the pleats. For that you need a proper degreaser soak, ideally every time you clean the filter, not just occasionally.
How long should I soak a pool filter cartridge in muriatic acid?
No more than 10 to 15 minutes, in a solution diluted to roughly 1 part acid to 20 parts water, and only after degreasing first, since acid dissolves mineral scale, not oils. Leaving it longer risks damaging the pleated filter material.
How long do pool filter cartridges last?
Typically 1 to 3 years with regular cleaning, though a heavily used pool can wear one out closer to 6 to 12 months while an occasionally used pool might stretch a cartridge to 3 to 5 years. Torn, collapsed or permanently discoloured pleats mean it’s time to replace rather than clean.
Why does my filter pressure keep rising quickly after cleaning?
Usually because the cartridge is only being rinsed, not degreased, so oily residue keeps accumulating in the pleats. It can also mean the cartridge is nearing the end of its life and needs replacing rather than another clean.
