How Do I Clean a Pool Filter Cartridge?

Cleaning a cartridge means pulling it out, hosing every pleat clean, and soaking it if there are oils or mineral scale that water alone will not remove. Plan on doing this every three to six months for most residential pools.

The trigger to clean is not the calendar, it is the pressure gauge. When your filter pressure sits 8 to 10 psi above the clean, freshly serviced baseline, the cartridge is restricting flow and needs attention.

Know your clean baseline

Right after you install a new or freshly cleaned cartridge, with the pump running normally and air bled out, write down the pressure reading. That number is your baseline, and it is specific to your system. There is no universal correct psi.

From then on, clean when the gauge reads 8 to 10 psi above that number. Ignoring a high reading starves the pump, reduces turnover, and shortens pump life.

Step by step cleaning

1. Turn off the pump at the breaker. Do not skip this.
2. Open the air relief valve on top of the filter tank and let all pressure bleed off until the gauge reads zero.
3. Close the valves isolating the filter if your plumbing has them, then remove the clamp band or lid ring and lift the tank lid off.
4. Lift the cartridge straight out. Note the orientation if you have a multi-cartridge system.
5. Rinse loose debris off with a hose. Then, using a straight nozzle, work around the cartridge spraying down into each pleat from top to bottom, holding the spray at roughly a 45 degree angle so it lifts material out rather than driving it deeper.
6. Inspect the fabric. Look for tears, thin spots, crushed pleats and separated end caps. A damaged cartridge does not filter, and no amount of cleaning fixes it.
7. If the fabric still looks gray, greasy or gritty, soak it (see below).
8. Rinse thoroughly, reinstall, replace the tank o-ring after lubricating it with silicone based lube, reassemble, and open the air relief valve.
9. Restart the pump, let air purge until water sprays from the relief valve, then close it and record your new baseline pressure.

When rinsing is not enough

Rinsing removes dirt. It does not remove body oils, sunscreen or mineral scale, which are what actually clog the fabric long term.

For oils and organics, soak the cartridge overnight in a commercial cartridge cleaner or a degreasing solution, then rinse well.

For calcium scale, which feels gritty and looks whitish, soak in a dilute muriatic acid solution, always adding acid to water and never water to acid, and only after the oils have been removed first. Acid over an oily cartridge seals the grime in.

Wear eye protection and gloves, work outdoors, and rinse until no cleaner remains before the cartridge goes back in.

Common mistakes

Never use a pressure washer. It shreds the fabric and it is the fastest way to destroy an otherwise good cartridge.

Do not use household bleach, dish soap or laundry detergent. Soap foams endlessly in the pool and is very difficult to rinse out.

Do not run the pool without a cartridge, even briefly. Debris goes straight to the heater and returns.

Cartridges are consumable. Even with perfect care, most last two to five years. If pressure climbs back up within a few weeks of cleaning, the fabric is spent and it is time to replace it.

Cartridge care in the Florida Keys

Year round swimming means year round sunscreen and body oils, and no dormant winter stretch where the filter gets a break. Most pools here load their cartridges faster than a seasonal pool up north would, so the three month end of the range is more common than the six month end.

The lack of screen enclosures adds a steady stream of fine palm and plant debris to the mix, and our fill water carries enough hardness that scale on the pleats is worth checking for at every cleaning.

Salt air is the other factor. Filter clamp bands, bolts and pressure gauges corrode noticeably faster down here, so inspect the hardware every time you have the tank open and replace fasteners before they seize.

Keep two cartridges in rotation if you can, so you can swap a clean one in immediately and take your time cleaning and fully drying the other.