Filtration & Circulation /
When Should You Clean or Replace a Pool Filter Cartridge?
A pool filter cartridge should be cleaned when pressure rises or flow drops, and replaced when damage, stretching, or poor filtration persists.
Archive date: this article was written for PoolSkimmer on Oct 7, 2026 and given the earlier archive date of Aug 24, 2026 so the blog reads as an organized archive. It was not published on that date.
Signs your pool filter cartridge is due for some care
For a cartridge pool filter to perform as it should, water has to be able to pass through the pleats with ease. But once the cartridge is clogged with fine debris, oils, pollen and dirt, the system will have to labour harder and filtration will lag. You will know it is time to pay attention when you see any of the following:
- The pressure gauge is well above its clean baseline
- There is little return flow coming from the pool jets
- The pump is running but the water is still cloudy
- Debris makes its way back into the pool after you have vacuumed or brushed
Do not be fooled by what the cartridge looks like. It may appear only a little soiled yet still be impeding flow, particularly if there is microscopic matter lodged in the pleats.
Cleaning the cartridge
The rule of thumb is to service the filter when the manufacturer’s manual indicates it is due, or if rising pressure has begun to hamper circulation. Some pool owners will do this after a storm or a busy weekend, or whenever the water has been carrying an atypical amount of debris.
It is wise to establish a routine:
1. Note the pressure reading on a fresh or newly cleaned cartridge. 2. Use that as your benchmark for future checks. 3. When you see a marked increase in pressure or a drop in flow, give the cartridge a cleaning. 4. Have a look at other gear, like valves and baskets, which can sometimes give the impression of a clogged filter.
Safety first. Before opening the housing, the pump must be off. Put on appropriate PPE, including eye protection and gloves, and relieve pressure in the manner the equipment manual prescribes. One should never put a hand into operating suction or try to get at the skimmer basket with the pump on.
A proper way to clean
Take the cartridge out and rinse it from the top down to work the debris out of the pleats. Should the manual permit a more thorough job, stick to a product made for the purpose and heed the label.
Some good practices are to unclamp and remove components only as directed, to rinse the inside and outside of the pleats, and to let the unit dry if periodic deep cleaning is called for. Once the cartridge is back in place, check the gauge.
Keep the pressure washer at a distance; going too close to the media can ruin the polyester fabric and cut the life of the cartridge. While you are at it, take stock of the o-ring, tank and top manifold to make sure a minor leak is not being attributed to the cartridge.
Time for a new one?
All the cleaning in the world will not help if the cartridge is no longer sound. Make plans to replace it if you find:
- Any tears in the pleats, broken end caps or seams that have come apart
- Fabric that is fraying, brittle or stretched
- Pleats that have gone flat and will not rebound
- High pressure or weak flow that persists even after a good cleaning
If you find yourself replacing the cartridge with increasing frequency, the problem could be with the filter sizing or something else in the system. In such an instance, upgrading to a larger cartridge pool filter might be a more sensible long-term solution.
Post-installation
Once a new cartridge is in, fire up the pump and verify that pressure and flow are back to normal. Check the lid, pipe fittings and housing for any leaks. If the numbers are still off, put a stop to it and have a look rather than forcing the system.
There are a few pitfalls to avoid, such as reinstalling a compromised o-ring, or making the assumption that cloudy water automatically means the cartridge has to go. And always read the manual and chemical labels; do not just wing the cleaning process.
Know when to get help
If the filter housing is leaking, or the pool stays cloudy with everything appearing in order, it is best to call a qualified professional. The same goes for a stuck valve or if the pump will not hold its prime.
And under no circumstances should anyone be in the pool if the water is not safe or there are electrical issues. If breakers are tripping or you spot arcing and damaged wiring, clear the area and arrange for service without delay.