How to Clean a Cartridge Filter

While cleaning the leaves and muck from your swimming pool may seem to do the trick, the cartridge filter does most of the hard work. Your cartridge filter collects all algae and other microbes as water is pumped through it. Over time, these filters accumulate a lot of dirt and debris, which needs to be manually cleaned for the filter to continue functioning optimally and keep your pool water clean.

In this article, I will provide a helpful guide to cleaning the cartridge filter yourself, the supplies you will need, and answer any questions you might have.

Step-By-Step: How to Clean Your Pool Filter Cartridges

Cleaning your cartridge filter doesn’t have to be expensive or difficult. Unlike other filter types, you will not need to backwash a cartridge filter like a DE or sand filter. It just requires a couple of supplies to complete the job successfully and quickly. You’ll need:

  • Garden hose
  • Bucket
  • Commercial filter cleaner or dishwashing liquid
  • Muriatic acid

Step one: Turn off the filtration system

The first step to cleaning the cartridge filter is turning off the power to your filtration system in your pool. This includes turning off any timers that might turn it back on while cleaning the filter.

Step two: Bleed air

Once your filtration system has been turned off, you will need to bleed the compressed air. You do this by opening the air relief valve, which removes air from the filter. This also drains the filter of any excess water from the pool.

Step three: Remove the cartridge filter

Depending on your model, undo the tension clamps, knobs, or lock-ring, and remove the cartridge filter from its filter unit. If you are unsure how to remove the filter, check the manufacturer’s guide. This should advise you on how to remove the filter without damaging anything.

Step four: Wash the cartridge filter

Wash the cartridge filter using a simple garden hose by spraying water at a 45-degree angle with a gentle nozzle. Do not use a powerful spray like a pressure cleaner, as it will only damage the pleats on the filter. Since cartridge filters do not require backwashing, you will use a hose to clean them.

It is best to start at the top and work your way down, going over all sides of the dirty filter. Once cleaned, rinse and repeat the process until the filter looks clean or the water is clear. Make sure to gently wash in between the pleats.

After the first cleaning, you may notice that your filter doesn’t look as white as a new filter. This discoloration is entirely normal; it will still be clean.

Step five: Soak the filter

Sometimes, you will need to soak the filter to remove the stubborn debris. Oils from sunscreens, perspiration, and tanning lotions can accumulate in the filter. Soaking the filter in a commercial filter can help remove the leftover oils. If you don’t remove the oils trapped in the filter, it can clog up the pleats, making it impossible for the filter to do its job correctly.

To remove the oils, place your cartridge filter into a large bucket and fill it with a mixture of water and a commercial pool cleaner. If you don’t have a specified pool cleaner, you can use one cup of dishwashing liquid mixed into five gallons of water.

The filter should be soaked for up to 10 hours, depending on how stubborn the dirt and debris are. If you’re in a hurry, I recommend soaking for no less than 1 hour.

Step six: Rinse off the filter

Remove the filter from the bucket and rinse off the pool cleaner.

Step seven: Soak again with muriatic acid

If your filter still has algae, iron, calcium carbonate, and other minerals on it, then you will have to soak it again. This time, soak it in a mixture of one part muriatic acid to twenty parts water. Place the filter into the mixture and let it soak until the bubbling stops completely. Then remove it from the mixture.

Step eight: Rinse again

Once removed from the mixture, rinse the cartridge filter thoroughly to ensure no muriatic acid is left on the filter.

If your filter is still dirty after following these steps, it may be time to invest in a new cartridge filter. On average, cartridge filters must be replaced every 3-5 years.

Step nine: Put back the cartridge filter

Now that your filter is sparkling clean, place it back into its housing unit, ensuring all parts are in the correct place and that the filter is secured correctly.

Step ten: Turn on the filtration system

The final step is to turn the air filtration system back on. You will notice that your clean filter will result in a stronger pool cleaner suction, increasing water flow.

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Frequently Asked Questions

How often do you clean a cartridge pool filter?

Cartridge filters typically need to be cleaned around every 2-6 weeks, depending on your filter size and how much debris you have in your water.

For example, if your pool is directly underneath a tree, there will be more dirt and debris, meaning your filter is working extra hard to clean it. This will result in the filter needing to be cleaned more often.

By cleaning your filter regularly, you can expand the life of the filter, saving you money in the long run.

When do I know it’s time to replace my filter cartridge?

You can use a few different methods to determine when to replace your cartridge filter.

If you notice that your pool is producing murky water even after cleaning the pool and filter, it is likely time to replace the filter.

If you have cleaned the filter thoroughly and soaked it in cleaner and muriatic acid and the filter cartridge is still full of debris and mineral build-up, this is another indication that it may be time to throw the old one out and buy a new one.

Remember that the filter will need replacing every 3-5 years, so it is normal to purchase a new one once in a while.

How do I get rid of really stubborn debris?

Sometimes, washing your filter with a hosepipe isn’t enough. Dirt and debris can get stuck inside the pleats of the filter, negatively affecting the quality of your pool water. The most common debris you’ll find in your filter is silt, leaves, and fibers.

To get rid of really stubborn debris, hold the cartridge at an angle of 45 degrees so that the water can penetrate the dirt in between the pleats. Another helpful trick you can use to clean the debris is to gently brush the pleats to remove debris. Do not use a pressure washer – this will damage the cartridge fabric.

If all else fails, you can always soak your cartridge filter in a large bucket of commercial filter cleaner for up to 10 hours. This way, you’re ensuring all debris is cleaned out.

Bottom Line

Cleaning your cartridge filter every 2 to 6 weeks should be a routine part of your pool maintenance and will ensure that your pool water quality is at a high standard. Follow my step-by-step guide, and you can expect clean water and a long-lasting filter. A consistent cleaning schedule will keep the cleaning process super easy and efficient, saving you money and time in the long run.

For more information on cartridge filters, check out my cartridge filter basics guide, how to solve common pool cartridge filter problems, and my picks for the best pool filter if you need some new recommendations. I also cover how to clean other types of pool filters in my main how to clean a pool filter guide.

Any more questions? Let me know; I’m happy to help.

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