An In-Depth Cleaning Guide For Your Pool’s Cartridge Filters

While owning a pool brings many great benefits to any home, regular maintenance is essential — and that includes cleaning the filter. Cartridge filters in particular need to be cleaned frequently in order to run effectively, and the cleaning needs to be done properly to prevent damage.

Cartridge filters need to be cleaned every few weeks (depending on how heavily you’re using your pool at the time). The process includes gently rinsing and brushing the filter, bathing it in trisodium phosphate powder and hydrochloric acid, and applying silicone paste as needed.

Let’s take a closer look at cleaning your cartridge pool filter, including how often you need to do it and the steps you should take before beginning the process.

What Is a Cartridge Pool Filter?

A cartridge pool filter (on Amazon) is a cylindrical-shaped filter that uses a cloth-like material to filter out any debris and dirt you don’t want to find in the water. These filters are easy to use and relatively inexpensive, making them a popular middle-of-the-road filter choice for the average pool owner.

What Supplies Do You Need to Clean Pool Cartridges? 

A man checks a filter for cleaning a home pool -

Before you begin cleaning your pool cartridges (or well in advance), you should make sure you have the following supplies at the ready:

Trisodium Phosphate Powder

Trisodium phosphate powder (on Amazon) will be the main cleaning ingredient for your pool cartridges. If you don’t have this, you can also use a dishwater detergent, though it’s highly recommended to use the trisodium phosphate powder (TSP) specifically since it’s been tried and proven to be effective and safe.

Hydrochloric Acid

Hydrochloric acid (on Amazon) will help to get all of the harder substances out of the filter, such as minerals that have built up. Make sure you handle this safely, using protective gloves and goggles so as not to get it on your skin.

Silicone Paste

If you need to fix any of the rubber seals, silicone paste (on Amazon) is the most effective and inexpensive way to do so. Having some handy means you won’t run into any snags when cleaning your pool cartridges if some minor repairs need to be made.

Plastic Trash Can

You’ll need a plastic trash can to bathe the filter in. Around 50 gallons should be ideal — though if you’re unsure of how much you’ll need, it’s always best to go bigger.


In addition to the cleaning supplies, you’re also going to need some tools to help you out with the job, including:

  • A hose with different spray settings so you can figure out which one works best (Don’t use a pressure washer)
  • Paper towels and old rags to clean the cartridge
  • A rubber mallet, a drive ratchet, and a drive torque wrench for removing and securing the cartridge
  • Safety gloves and glasses
  • A measuring cup (on Amazon)

Note: Although you may have a measuring cup lying around, it’s best to use one dedicated to this purpose as you’ll be putting some harmful chemicals in it. It’s not a good idea to use it for cooking later.

How Often Do You Need to Clean Your Pool’s Cartridge Filters?

How often you need to clean your pool’s cartridge filters depends on how often you use the pool. At the absolute most, you can go six weeks without cleaning the cartridge filters. Two to four weeks is more common and, with heavy use, you should be cleaning the cartridge filter every two weeks.

What to Do Before Cleaning 

Let’s take a more in-depth look at the steps you should take before you actually get to cleaning the cartridge.

Turn Off the System

The first thing you should do is make sure the system is completely turned off. Close the valves and make sure the pump isn’t running, or you could do damage to the system removing things — or worse, hurt yourself.

Remove the Filter

Remove the filter the proper way. You’ll first need to use the socket and ratchet mentioned earlier to remove the bolt that’s holding the clamp together. If it’s stuck on, use a rubber mallet to gently loosen it. This should then expose the filter.

How to Deep Clean Your Cartridge

Now that you’ve removed the filter, you can get to cleaning out the debris and putting it back in the pool. Here are the steps to take to make sure it’s completely clean.

Rinse and Brush

The first thing you should do is rinse the cartridge with the hose and gently brush it down (if you need to). Make sure you’ve gotten as much of the debris off as you possibly can this way.

Bathe in TSP

You’ll want to use one cup of TSP for every five gallons of water. Create a bath in your plastic bin and then place the filter in there to soak for a few minutes. While you’re doing this, you can rinse off the inside of the filter housing. Make sure you rinse it off when removing it from the bath.

Bathe in Hydrochloric Acid 

Use one part hydrochloric acid per twenty parts water and bathe it in that next. How long you need to bathe depends on if a lot of algae or bacteria has collected on the filters. You could bathe it for a few minutes, or go as long as overnight but once it’s done, make sure you rinse it thoroughly.

Reassemble Your Cartridge Filter

Once you’ve done that, it’s time to reassemble the cartridge filter. Check the conditions of the seals first so you can apply silicone paste if you need to. You shouldn’t have to do this every time, but it’s handy to have it on hand for when necessary. You can then reinstall the clamp and tighten the bolt before turning your system back on.

What Not to Do When Cleaning Your Cartridge Filter 

Cartridge filter

There are a couple of things you should avoid doing when cleaning your cartridge filter, as they can cause damage to it.

The first is using high pressure from the hose. While firm pressure is fine, you don’t want to soak the cartridge with so much water that it ends up getting damaged from the strength of the jet of water.

The second is using a rough brush or scrubbing it too hard to get everything off. While brushing the cartridge down is fine before soaking it, you should use a very gentle brush and mostly rely on the baths to get everything off.

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