How to Clean Your Pool's Cartridge Filter

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How to clean a cartridge pool filter

Cartridge filters are one of the three most common pool filter types on the market, alongside sand filters and DE filters. They’re also arguably the least maintenance-heavy among the three, and they’re definitely the easiest to clean.

That comes at the cost of efficiency (cartridge filters are not as thorough as DE filters) as well as a potentially greater financial cost (sand filters can be cheaper). But for most pool owners, cartridge pool filters have the immense advantage of getting the job done while remaining easy to clean. Here’s how to do it:

Cleaning your pool’s cartridge filter

As with most pool filters, the cleaning process mostly involves taking the filter tank apart, removing the filter medium (a cloth cartridge, in this case), and cleaning it – either with a hose, or via a more intense chemical cleaning process.

Let’s go through the steps together, one by one:

  1. Turn off the pump. The first thing you want to do is make sure that your pump isn’t pulling water.
  2. Turn the air relief valve. Pool pumps shouldn’t have air in them. The air relief valve is designed to rectify that problem – and release a little pressure, so you can easily open the filter up.
  3. Open the filter. Most filter tanks come with easily removable latches, and a top or housing, giving you access to the cartridge inside.
  4. Remove the cartridge and set it aside. Once you’ve removed the cartridge from the tank (carefully), give it a thorough inspection. Is it cracked anywhere? Is there any noticeable tearing or damage to the fabric? If yes, you may need to consider replacing the cartridge instead of just cleaning it out. If not, you can do one of three things. First, hose it down with water. Get in between the pleats and use a 45-degree angle. This is a light cleaning, for when the filter is a bit dirty, but not necessarily in need of a deep or thorough wash. Second, use a cartridge filter cleaner. You will want to buy and use the right filter cleaner depending on the manufacturer and type of filter (cartridge, in this case). Most filter cleaners come with their own set of instructions depending on their contents. Many filter cleaners can be used without having to take the pump apart at all, by pouring a set amount into the pump skimmer. Third, soak the filter overnight. If it’s really, really filthy, you can soak the cartridge in a cleaning solution overnight and see if that does the trick. Be sure to dilute the cleaner with water as instructed on the packaging and use a container large enough to completely cover the filter.
  5. Check the integrity of the filter tank. Once you’ve successfully cleaned the filter out, see how the tank is doing. Check for signs of damage or corrosion. Check the O-ring near the middle of the filter to see if it’s well-lubricated (otherwise, you might get a pump leak). We always recommend changing out the tank o-ring on each clean. It will save you time and money in the long run as they are relatively inexpensive. Then, put the cartridge back in and close the tank up.
  6. Turn the pump back on. Keep the air valve open until water spurts from it. Finally, check your water pressure. After a fresh clean you should be running around 10-15psi.

At this point, your pool cartridge should be clean. A telltale sign of a clean cartridge is normal water pressure in your pump.

If you haven’t previously recorded what normal water pressure should be the last time you cleaned your filter, consult your owner’s manual for more information. It should contain the acceptable PSI range for a cleaned filter (as well as at what point you should consider cleaning it again).

Pool pump water pressure is a decent metric for when to clean out a filter, as the water pressure increases the more clogged the filter gets.

Cartridge pool filter vs. other pool filters

Cartridge pool filters are made of a polymer cloth that filters particles as small as 25 microns – not quite as impressive as the more expensive DE filters, but enough to filter things you can’t even see (human hair is about 50-90 microns in thickness, by comparison, and the human eye ceases to reliably see something past 40 microns).

The cartridges in a cartridge pool filter tend to be replaceable and are meant to be replaced about once every three to four years.

Other pool cartridge filter maintenance tips

A pool filter only gets as dirty as the pool does. You can help reduce the frequency of your filter cleaning – and prolong the lifetime of both your filter and your pump – by regularly maintaining your pool. This means:

  • Checking the water balance often. A pool’s water balance is based on its alkalinity, calcium hardness, chlorine levels, and pH value. At the right levels, a pool should neutralize most bacteria and algae, stay clear, avoid damaging its lining, and avoid calcium deposits (or scaling) on its walls or pipes. But over time, a pool’s water balance can change drastically, leaving the filter to do more work.
  • Keep your pool free from large debris on a daily basis. Put that pool skimmer to good use! Large debris left floating for too long will eventually break down in the pool water, staining your pool.
  • Taking care to avoid unnecessary foliage around (and in) the pool. A little landscaping can go a long way. You can reduce the amount of stress your filters are put through by minimizing the amount of debris floating into the water. That might mean trimming some hedges and trees around the pool area.
  • Shock your pool with a chlorine shock (in the evening). Chlorine shocks are the most reliable way to get your chlorine levels back up and avoid cloudy or green water. But be sure to shock your pool as the sun sets. Sunlight can quickly neutralize chlorine.
  • Always maintain your filter and pool water after a storm. Storms can be a huge drain on your system, as your pool has to filter everything the wind and water swept into it. Most storms can lead to algae blooms the next day, as well as plenty of large and small debris in your strainer and filters alike. Be sure to give your pool a little love after a bout of bad weather.


Owning a pool can be an immense privilege – and, at times, a big chore. We can help you take all the guesswork and most of the legwork out of pool ownership with our pool maintenance tips and professional services.