How To Clean a Pool Filter Cartridge

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Be sure to clean your pool filter cartridge system as part of your pool winterization process. It's easy if you follow these steps.

In most parts of the U.S., winter means the end of outdoor pool enjoyment. Proper pool winterization involves testing and balancing pool chemicals. You’ll also need to clean your filters as part of periodic winter maintenance.

There are three main types of pool filtration systems: sand, dichotomous earth (DE) and cartridge. While all have their pros and cons, cartridge filtration systems are generally regarded as effective and easy to maintain with minimal technical know-how.

Here we’ll explore how to clean a pool filter cartridge system.

Why Do You Need To Clean the Pool Filter Cartridge?

Picture how an air conditioner, air purifier or even a cigarette filter function. Air passes through from one side and comes out cleaner on the other.

A pool filter cartridge works the same way, except with water, which passes from the intake pump and through the cartridge before exiting back into the pool.

Pool cartridges are round and cylindrical. They’re made of accordion-pleated polyester material that looks something like paper, only a lot more durable. They capture larger objects like leaves and dead bugs, as well as particulate and bacteria as small as 10 to 15 microns. (For some perspective, one millimeter equals 1,000 microns!)

Depending on the size of your pool and the setup of your filtration system, you may have one large filter or a few smaller, stacked filters.

The more you use your pool, the faster a filter gets dirty. And a dirty filter leads to problems like cloudy water, germs and bacteria, algae growth and scale buildup. In the worst case scenario, a dirty, clogged filter can make your pump work too hard to push water through and ultimately damage the motor.

How To Clean a Pool Filter Cartridge

If you cover your pool and shut off the pump for the winter, give your filter cartridges a thorough cleaning first. If you keep your pump running a few hours a day during the winter but otherwise don’t use the pool, clean filter cartridges once every three months.

(Note: This is for a winterized pool only. Clean the filters of pools in use at least once a month, or more often for a heavily used pool.)

Follow these steps to clean filter cartridges and ensure a healthily winterized pool.

Turn off the pump

Make sure the pump is off, and open the air relief valve to relieve any pressure before you open the filter tank.

Remove the cartridge(s)

Open the cylindrical tank that houses the filter or filters. Lift them out for cleaning.

Clean the filter with a hose

A garden hose with a nozzle sprayer attachment is your best tool for pool filter cleaning. It’s easy, but there are a few tricks to getting it right:

  • Set the filter on a flat surface where water will drain away.
  • Starting from the top of the filter, point the hose nozzle into each pleat. You should see debris washing away.
  • Once you’re gone around the entire filter, flip it over and repeat the process.
    • I’ve found this takes a few rounds, since the water pressure tends to push dirt from one section of the filter into another.
  • You can also clean with a hose attachment especially made for pool filters.

Or clean the filter with an air compressor

To conserve water or avoid getting wet, you can also clean your pool filter with an air compressor. Don’t set it on high, which can damage the filter. Do a test run with a low pounds per square inch (psi) setting, then build up to about a medium setting. You may still need to do a hose rinse afterward.

For winterizing, give the cartridges a soak

When you’re closing up the pool for the winter, it’s smart to soak the pool filters in a cleaning solution. To do this, you’ll need a bucket that’s taller than the cartridge. (For an extra-large cartridge, you may need a plastic garbage can.) Ratios and timing will depend on the cleaning solution you use:

  • One part water and one part household vinegar, soaked overnight.
  • One part muriatic acid to 20 parts water, soaked for about one hour.
  • For a prepared pool filter cleaning solution, follow the manufacturer’s instructions for ratios and soaking times.
  • Or opt for a spray and rinse cleaner and degreaser.

Soaking or otherwise cleaning pool cartridges with a chemical solution will clear away crusty, resistant build-up and ensure your filter is completely clean for winterization.

Put it all back together again

Once you’re satisfied the filter cartridges are clean, reinsert them and close up the tank, making sure to secure the pressure lock. Reactivate the pressure by closing the air release valve. Then turn on the pump to make sure everything is working properly.

Briefly open the air pressure valve to release any trapped air, then close it again. The pressure should rise to its proper range. Once that happens, your pool is good to go for the winter.

When to Replace Cartridges

Pool filters cartridges typically last about 2,000 running hours, or about one to two years. A busy pool filled with kids and sunbathers wearing lots of sunscreen will go through filters faster.

Every time you disassemble your filter housing, do a quick inspection. If the plastic filter frame is cracked, if the filter pleats are torn or looked “wilted,” or if the filter no longer comes clean with regular washing, it’s time to replace it.

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Elizabeth Heath
Elizabeth Heath is a travel, culinary and lifestyle writer based in rural Umbria, Italy. Her work has appeared in The Washington Post, HuffPost, Frommers.com, TripSavvy and many other publications. Her guidebook, An Architecture Lover's Guide to Rome, was released in 2019. Liz's husband is a stonemason and together they are passionate about the great outdoors, endless home improvement projects, dogs, their unruly garden and their slightly less unruly 8-year-old.