How to Clean a Cartridge Filter

Written by Michael Dean
October 25, 2023

dirty cartridge filters with question mark

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. Cartridge filters collect all the 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 cover my process for cleaning cartridge filters, the supplies you need, and answer common questions I get from readers and customers.

Main Takeaways

  • Cleaning your pool filter cartridges involves removing the cartridge filter after turning off the filter and bleeding the air, washing the cartridge filter, soaking it, and rinsing it off.
  • If the cartridge filter is still dirty, you may need to soak it in muriatic acid and rinse it off again before putting it back in and restarting the filtration system.
  • You should clean cartridge filters every 2-6 weeks.
  • It’s time to replace your cartridge filter if your pool is still murky after cleaning the pool and the filter, the cartridge filter is still full of debris after a thorough cleaning, or your filter is 2-4 years old.

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 the following:

  • Garden hose
  • Bucket
  • Commercial filter cleaner or dishwashing liquid
  • Filter Cleaner Spray
  • 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 must 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.

Step Three: Remove the Cartridge From the Filter Body

This step will be slightly different 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: Rinse Off the Cartridge Filter

Unlike other filter types, cartridge filters do not require backwashing, so you will use a hose to manually clean them. Wash the cartridge filter using a garden hose with a spray nozzle. Gently spray water at a 45-degree angle toward the filter. Do not use a powerful spray like a pressure cleaner, as it will only damage the pleats on the filter.

I find that it is best to start at the top and work your way down, going over all sides of the dirty filter.

Step Five: Spray the Filter With a Cleaning Spray

Once you have thoroughly rinsed the pool filter, use a commercial pool spray to clean the filter. Spray the entire filter, wait 10 minutes, and then rinse the filter thoroughly. If your filter is not overly dirty, you may be able to get away with simply using a spray and rinsing it off a few times.

Step Six: Soak the Filter

If your filter is extra dirty and filled with stubborn debris, you may need to soak it overnight to clean it. Oils from sunscreens, perspiration, and tanning lotions can accumulate in the filter, which can be difficult to remove by simply spraying and rinsing it. 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. Make sure to follow the directions of your commercial filter cleaner; most recommend mixing one bottle of cleaner with five gallons of water. 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 4 hours.

Step Seven: Rinse Off the Filter

After allowing your pool filter to soak for at least four hours, you can remove it from the bucket and thoroughly rinse it with your garden hose. Make sure to rinse off all of the pool cleaner or dish soap. Check the filter; if there is still a good amount of debris and buildup, you’ll want to soak it again.

Step Eight: Soak Again With Muriatic Acid

If your filter still has algae, iron, calcium carbonate, and other minerals on it, you’ll need to soak it again to get rid of the buildup. This time, break out the big guns and 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. This should only take around 10 to 15 minutes. Do NOT leave the filter in the solution for more than 20 minutes! If you soak it for too long, you risk damaging the filter.

Step Nine: Rinse Again

Remove the cartridge filter from the muriatic acid solution and thoroughly rinse it. Check the filter again. Is there still algae or mineral buildup on the filter? If so, it may be time to invest in a new filter cartridge. Filter cartridges should last you 1 to 2 years, so it is possible that it is simply time for a fresh filter.

Step Ten: Put the Cartridge Filter Back

If your cleaning worked wonders and your cartridge is now sparkling clean, place it back into its housing unit, ensuring all parts are in the correct place and the filter is secured correctly.

Step Eleven: Turn On the Filtration System

The final step is to turn the pump/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 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 methods to determine when to replace your cartridge filter.

If you notice that your pool produces 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 buildup, this is another indication that it may be time to throw the old one out and buy a new one.

Remember that the filter cartridge will need replacing every 1 to 2 years, three years at a push, so it is normal to purchase a new one occasionally.

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 in your filter is silt, leaves, and fibers.

To get rid of stubborn debris, hold the cartridge at an angle of 45 degrees so that the water can penetrate the dirt between the pleats. Another helpful trick to clean the debris is gently brushing the pleats to remove it. 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.

Can you use dish soap to clean a pool cartridge filter?

Absolutely! Dish soap works great as a cartridge filter cleaner and is an excellent, affordable alternative to a specialized cartridge cleaner! I personally use dish soap to soak and clean my cartridges. Simply dissolve 1 cup of dish soap into 5 gallons of water, and you are good to go!

Can you clean a cartridge filter with vinegar?

You can definitely use vinegar to clean an extra dirty pool cartridge filter! Vinegar especially works wonders on cartridges with lots of calcium buildup. Depending on how bad the calcium buildup is, you can soak it in straight vinegar or a solution. For minor buildup, soak the cartridge in a solution of 1 part vinegar and 1 part water. You should soak the filter for at least 4 hours; ideally, it should be soaked overnight.

Do you backwash a cartridge filter?

Cartridge filters are the only type of pool filter that you do not need to backwash. This makes them the most efficient in terms of water consumption. That said, you will need to manually wash your pool filter to keep it clean.

A Clean Filter = A Clean Pool!

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 make cleaning 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.

Need more advice on cleaning your cartridge filter? Feel free to reach out to me! I am always happy to help.

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