How to Clean the Pool Cartridge Filter (Using Hydrochloric Acid) (2023)

A clean pool depends heavily on clean filter cartridges. The problem is that cartridge filter cleaning methods like hosing down do not thoroughly clean a filter. But don't worry, this post shows how you can easily clean your pool's cartridge filter with muriatic acid.

Let's dive in.

How to Clean the Pool Cartridge Filter (Using Hydrochloric Acid) (1)

How to clean pool cartridge filters with muriatic acid

Cleaning the cartridge filter of your pool with hydrochloric acid is carried out as follows:

  1. Turn off the pool pump
  2. Open the filter canister (release the pressure first) and remove the cartridge filter(s).
  3. Fill a trash can with a 20:1 ratio of muriatic acid to water
  4. Soak the cartridges in the hydrochloric acid solution for 1 hour
  5. Rinse the cartridges with a garden hose and reinstall

Read on for a detailed guide on using acid to clean your pool's filter cartridges.

How to Clean the Pool Cartridge Filter (Using Hydrochloric Acid) (2)

What clogs cartridge filters?

The cartridge filter in your pool keeps the water clean and safe. As the water flows through the cartridge filter, the elements in the filter catch debris floating in the water.

Over time, the filter will pick up oils, dirt and limescale deposits on the filter elements, which can clog the filter. This can be difficult to clean up with a hose or regular filter cleaner. In this case, you should soak and wash the cartridge filter in hydrochloric acid.

Another thing that clogs cartridge filters is DE (diatomaceous earth). Some pool owners have experimented by adding this to their filter. Read more in our article:Can you add DE to a cartridge filter? (Answered!)

What you need to acid clean your pool filter

But before you can wash the cartridge filter in hydrochloric acid, you need a few things:

Acid Resistant Gloves

safety goggles

A big trash can

(Video) How To Deep Clean Your Pleated Pool Cartridge Filter

hydrochloric acid

garden hose

A soft brush

Instruction manual (optional)

A wrench (optional)

Cartridge filter change (optional)

acid neutralizer

Filter cleaning instructions (detailed version)

Let's get to work now. Here is the detailed guide to cleaning your pool filter with muriatic acid.

1. Turn off the pool pump

The first step is a precautionary tip. You should never work on your pool equipment when the pump is on to avoid damage and injury.

So, unplug the power cord or turn off the pool's pump at the breaker.

2. Open the filter case and take out the cartridge filter

The next step is to open the filter canister so you can access the cartridge filter.

Before doing this, you must open (or bleed) the bleed valve to release the air pressure in the filter canister. There is usually a lot of pressure in the filter canister. If you open the tank directly without deflating, the cap may come off and cause injury. So first release the pressure.

The filter canister is usually covered with a lid and this lid is clamped on with either an O-ring or a metal clamp held in place with screws.

(Video) How To Acid Wash A Cartridge Filter

If your pool has an o-ring clamp, you should follow the instructions in the owner's manual to open it. Most o-ring clamps can be opened by depressing the release tab and turning the locking knob to the left (or counterclockwise).

If the filter tank lid is held in place by a metal bracket and screws, you must loosen the screws to open the filter tank. This is where the wrench will come in handy.

When opening the filter container, carefully pull out the cartridge filter. Depending on your pool model, you may have more than one cartridge filter in the filter housing. So make sure you remove all filters.

3. Prepare the filter acid cleaning wash

You should never wash your cartridge filters with muriatic acid straight from the container. This is because the acid content makes the elements too aggressive and can damage the cartridge filter.

The acid is also strong enough to cause health problems. Make sure you use safety goggles, wear long-sleeved clothing, andAcid Resistant Gloves.

Mix the muriatic acid with water in a trash can to dilute the acid. A safe formula for cleaning pool filters is to mix hydrochloric acid and water in a 1:20 part ratio. That means you should mix 1 part acid to 20 parts water.

After mixing the acid with water, let the solution sit for a few minutes to allow it to settle.

Note: Do not use cyanuric acid to clean your pool filter. Cyanuric acid and hydrochloric acid are very different. We have another article that explains thatDifference between cyanuric acid and hydrochloric acid.

4. Soak the cartridge filters in the hydrochloric acid solution for 1 hour

Gently lower the cartridge filter into the hydrochloric acid solution and leave for an hour.

As you soak the filter in the hydrochloric acid solution, you may notice bubbles forming at the top of the solution - as if air is escaping from under the solution. This bubbling shows that the filters are being cleaned.

If you don't notice any blistering, don't panic. The absence of bubbles means that the filter is not dirty. So top marks for you for excellent filter maintenance.

After one hour, remove the cartridge filters from the solution.

If you still notice dirt in the filter elements, you can brush over the pleats with a very soft brush. This will remove any dirt that has become lodged in it. Never use a stiff brush on the filter elements to avoid damage.

(Video) How To Acid Clean Your Cartridge Filters

Note, however, that the filter will likely still look dirty after soaking - it will dissolve just fine when we rinse it out in the next step.

5. Rinse and reinsert the cartridge filter

After an hour, you should remove the filter from the acid solution and rinse it with your garden hose. Be sure to hose down the cartridge filter vigorously with the garden hose. This will ensure the filter is sparkling clean as desired.

Next, check the cartridge filter for damage. If the cartridge filter is worn out or damaged, that meansIt's time for a replacement.

Now put it back in place, making sure to put the filters back the way they came out.

How to dispose of the hydrochloric acid solution

The acidic solution you used to wash your filter is corrosive and you should neutralize it before disposing of it. You can neutralize it with borax,Backsodaand/or soda. Just add one of these to the acid solution and stir as you go.

It will be bubbly, so make sure you still have your safety gear on. Add one of these until it stops bubbling.

You may now dispose of it down the sewer if your state or local laws allow it.

See our for detailed instructionsother post here.

Is it safe to clean the pool filter with muriatic acid?

Cleaning the filter of a pool with acid is safe. It should only be done twice a year. Acid is strong and will break down the adhesives and materials in the filter, so limit the frequency. You should always use a dilute acid solution and never 100% acid.

Now that you know how to safely clean your cartridge filters with muriatic acid, how often should you clean your pool filters? Let's take a closer look.

Related reading:Using muriatic acid to quickly clean a green pool

How often should you wash your pool's cartridge filter?

You should hose wash your pool's cartridge filter every month to ensure peak performance and durability of the filter elements. The filter(s) should be sprayed hard with your garden hose.

For a more thorough cleaning, use a cartridge filter cleaner. And for a deep clean, use muriatic acid - but only once or twice a year as it will corrode your filter.

(Video) 4 Ways To Clean Your Pool Cartridge Filter

Your pool's cartridge filter catches a lot of dirt in the water. Algae, leaves, hair care products, body oils and food particles are among the few contaminants your filter elements will retain in the water. Over time, these contaminants accumulate in the filter elements and you need to clean them.

It is important that dirt does not build up in the filter elements, so you should flush the filters with clean water every month or more often during the peak season. Also, you should soak the cartridge filters in chemicals every 3 months.

You will need to clean your filter more often if you use the pool a lot, it has rained heavily, or you have had algae in the pool. And if you have a lot of trees near your pool, cleaning your filter once a month probably won't be enough - try every week.

A good filter cleaning routine will ensure your pool stays safe, clean and healthy. But how do you know when the cartridge filters need to be cleaned? Read on to find out.

How do you know when to clean your pool cartridge filter?

You can know when to clean your pool cartridge filter by checking the filter pressure gauge. The ideal filter pressure for a pool is between 8 PSI and 15 PSI (pounds per square inch). Any reading above this range is an indicator that you need to wash the cartridge filter.

How to Clean the Pool Cartridge Filter (Using Hydrochloric Acid) (3)

You should also clean it after heavy rain, many bathers or after algae infestation.

Can you backwash a pool cartridge filter?

Pool cartridge filters should not be backwashed as this can damage the filter elements. Backwashing the filter elements does not clean the filter particularly well either. This is because some dirt is embedded deep within the filter elements and cannot be removed by hosing down alone.

Instead, you can deep clean pool filters by soaking them in pool filter cleaner. You can get a pool filter cleaner at any hardware or pool store. A thorough cleaning of the filter removes stubborn embedded stains such as slime, algae, limescale, oils and sunscreen.

What else can I soak my pool filter in to clean it?

You can soak your pool filter in:

Many pool filter cleaners contain acids. However, they are not as strong as soaking in muriatic acid.


Overall, cleaning your pool's cartridge filters with muriatic acid is a fairly simple process. All you have to do is mix the muriatic acid with water in the right proportion and soak the cartridge filters in the solution. Try it and you will be surprised how well it works.

Related reading:
What is hydrochloric acid in a pool for?
Easy way to remove algae from a pool filter cartridge
Neutralize and clean up a muriatic acid spill (near a pool)
What is a normal pool filter pressure range?
Can you convert a pool from a cartridge to a sand filter?

(Video) Acid Washing Your Cartridge Filters


How do you clean a pool cartridge with muriatic acid? ›

Open The Filter Tank (Releasing the Pressure First) and Take Out The Cartridge Filter(s) Fill Up a Trash Can with a 20:1 Ratio of Muriatic Acid and Water. Soak the Cartridges in the Muriatic Acid Solution for 1 Hour. Rinse Cartridges with a Garden Hose and Reinstall.

What can I use to clean my pool cartridge filter? ›

The most common approach for cartridge cleaning is to use water—a hard spray from a garden hose. In a few minutes, the water will rinse away debris from between the folded cartridge pleats. Begin at the top of the cartridge, and work your way toward the bottom.

How long should I soak my pool filter in muriatic acid? ›

Here's how to clean a D.E. filter using muriatic acid: Backwash the filter for 3–5 minutes until the water runs clear. Power the pump off. Open the filter's air relief valve and remove the drain plug, so that water drains out of the filter tank.

Is muriatic acid the same as hydrochloric acid? ›

Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid.

Can I use hydrochloric acid to clean my pool? ›

When placed in pool water, hydrochloric acid has proven to be profoundly effective at removing algae from the floors and walls of a pool while also lowering pH levels that have become harmful to your health.

What kind of acid do you use to clean pool filters? ›

To put that in perspective, the smallest the naked eye can see is 35 microns. Many DIY folks turn to trisodium phosphate (TSP) and muriatic acid to clean their pool filters. Both TSP and muriatic acid are toxic and require you to wear protective rubber gloves, goggles and a mask when cleaning.

What is the best pool cartridge filter cleaner? ›

  • 1 Black Diamond Pool Filter Cartridge Cleaner – Best Overall.
  • 2 Spa Depot Pool Filter Cartridge Cleaner – Runner Up.
  • 3 MAV Aquadoc Pool Filter Cartridge Cleaner – Honorable Mention.
  • 4 HTH Pool Filter Cartridge Cleaner – Also Consider.
Dec 23, 2022

Can you use bleach to clean pool cartridge filters? ›

Companies that sell pool chemicals advise against doing so, since bleach can damage the fibers of your filters and thereby shorten your filter life.

How do you clean water filter cartridges? ›

Is it Ok to Clean Water Filter Cartridges? Some might think that cartridges can be cleaned by boiling them or rinsing them with water, which is false. Generally, you should never clean the cartridges in your water filter. Trying to clean your cartridges instead of replacing them can have serious consequences.

Can you pressure wash cartridge pool filter? ›

Clean the cartridge using a spray nozzle on your garden hose — spray at an angle to get between the pleats. Never use a pressure washer; it will damage the cartridges.

How often should you clean a cartridge pool filter? ›

A commonly asked question amongst our customers is, “when should we clean our pool's filter cartridge?” Typically, we recommend that your cartridges inside your filter be cleaned every 3 months for longevity of your cartridges, as well as for better pool filtration and water flow.

Should I run the filter after adding muriatic acid? ›

Keep your pump on for at least 30 minutes immediately after adding the muriatic acid. Again, be sure your pump is set to “circulate” to help the muriatic acid mix in. This will prevent the acid from damaging your pool surfaces.

What happens if you put too much muriatic acid in pool? ›

If you use too much muriatic acid, your pH will drop to dangerously low levels. Metals in your pool, such as railings, ladders, bolts, screws, and other important equipment, can be damaged by low pH levels.

How do you use hydrochloric acid in a pool? ›

General Instructions
  1. When adding Hydrochloric Acid ensure that the product is mixed thoroughly with water remembering to always add acid to water, never add water to acid.
  2. Apply the mixed chemical to the surface of the pool water.
  3. Allow 2-3 hours mixing with the filter running before measuring pH again.

Can I use hydrochloric acid instead of muriatic acid? ›

There are three very common types of acid that can be used in water, which include muriatic acid, hydrochloric acid, and sulfuric acid. Both muriatic acid and hydrochloric acid are highly similar in composition. In general, muriatic acid is a less pure form of hydrochloric acid.

Is hydrochloric acid and pool acid the same? ›

Hands down, the most common acid in the pool business is Hydrochloric Acid (HCl), aka muriatic acid. As we have discussed in other articles, acids have a higher concentration of Hydrogen. Since its pH is less than 1.0 (<1.0 pH), muriatic acid is over a million times more acidic than neutral water (7.0 pH).

Is hydrochloric acid stronger than vinegar? ›

Acetic acid (CH3COOH) present in vinegar is a much weaker acid than hydrochloric acid, and so it cannot displace the latter from its salt.

How long does hydrochloric acid stay active? ›

These alkaline and acidic chemicals like hydrochloric acid can last for over five years, but we strongly suggest that you just get enough for one season and reorder a new batch the next season.

Is hydrochloric acid the same as chlorine? ›

Chlorine, usually in solid tablet or liquid form, is a strong antibacterial agent used to treat the water to keep it clean and germ- and algae-free. Hydrochloric acid, on the other hand, has a number of uses, including cleaning pool tiles and - when used very, very carefully! - lowering the pH of pool water.

Is pool chlorine the same as hydrochloric acid? ›

Chlorine turns into hydrochloric acid when it gets into your pool that disables bacteria, viruses, and any other microscopic organisms lurking in the water. Combined chlorine is called chloramine. Generally speaking, the dose you use is safe for people.

Can I use muriatic acid to clean my pool filter? ›

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.

Can an acid wash damage a pool? ›

If your pool has a pebble, plaster, or quartz surface, it is safe to acid wash. If your pool is vinyl, fiberglass, acrylic, or painted, acid washing will cause damage. In Arizona, there are many examples of a concrete pool, but note that even these will receive damage from acid if the task is not done properly.

How much acid do you need to clean a pool cell? ›

Even self-cleaning (reverse polarity) cells need cleaning occasionally. Make a cleaning mixture of 1 Hydrochloric Acid to 10 parts water (always add Water first then the Hydrochloric acid to the water).

What is the life expectancy of a pool cartridge filter? ›

Pool filter cartridges can run for about 2,000 hours in a filter pump and should be replaced every 1-2 years. Note that the filter cartridge will not last as long due to sunscreen, deodorants, hair care products, and other chemicals that come into contact with your pool water.

Why does my pool cartridge filter keep clogging? › explained that when your filter is brand new, water can easily pass through the system without issue. However, as the filter continues to do its job, debris can accumulate over time and slowly clog the system. As a result, pressure builds up within the filter and continues to rise if not cleaned.

Can you use vinegar to clean pool cartridge filter? ›

White distilled vinegar is a super versatile household cleaner used to clear up hard water stains, mold mildew, and algae. The downside of vinegar is that you have to use a lot of it. Generally, a one-to-one ratio of vinegar to water is needed to clear your cartridges adequately.

How do you clean a Hayward pool filter cartridge? ›

You local Hayward dealer should have a cartridge cleaner or you can use a mixture of laundry detergent and water. 1-cup detergent to 5 gallons of water. Dissolve the detergent in a bucket of water and soak the element(s) for 24 hours. YOU MUST THOROUGHLY RINSE THE ELEMENTS PRIOR TO REINSTALLING THEM INTO THE FILTER.

Can you clean a pool with hydrogen peroxide? ›

What you may not know is that hydrogen peroxide is a powerful oxidizer that can be combined with ultraviolet light to disinfect swimming pools. The combination of ultraviolet disinfection with hydrogen peroxide allows pool owners to safely eliminate all chlorine in their pool or spa.

How much bleach do I use to clean my water filter? ›

Purifying by adding liquid chlorine bleach
Treating water with household bleach containing 5.25-8.25 percent chlorine
Volume of Water to be TreatedBleach Solution to Add
1 gallon1/4 teaspoon
5 gallons1 teaspoon
10 gallons2 teaspoons
2 more rows

Can you clean and reuse filter cartridges? ›

No, it should not be reused. The cartridge should be changed at least once a month or when you see a noticeable decrease in water flow.

How do you remove calcium deposits from filters? ›

You can use vinegar to remove the build-up. If you don't have vinegar, you could also use lemon juice, although vinegar works best. Just put some on a clean cloth and rub over the calcium deposit. Rinse with warm water when you are finished.

Should I rinse filter cartridge? ›

Mechanical filter media (filter wool / pre-filter cartridges) can be rinsed under tap water. They serve no biological activity and need to be as clean as possible. Chemical media (Activated Carbon and Phosphate Remover) can be rinsed if particularly dirty.

Do you run the pump when adding muriatic acid? ›

The pump should run for at least half an hour to thoroughly mix the muriatic acid as it diffuses around the pool. If you'd like to aerate the pool longer and increase the pH a bit, keep running the pump or use an aerator/air stone to oxygenate the pool water.

Can I use muriatic acid to remove calcium deposits? ›

Muriatic acid is a strong hydrochloric-based acid, that is a great descaler. Because of the intensity of this acid, it has the ability to remove severe lime and calcium deposits found in pools and toilets.

How long do you let muriatic acid sit? ›

Brush or spray on a 1:10 diluted mix of acid in water onto the surface, allow it to sit for up to 10 minutes, but no longer, then spray it with a solution of 1 cup ammonia in a gallon of water to neutralize the acid. Allow the surface to dry completely before applying paint or other treatments.

Can I add a gallon of muriatic acid to my pool? ›

One gallon of muriatic acid will lower the alkalinity about 50 parts per million per 15,000 gallons of existing balanced pool water. So if you had a reading of 100 ppm and you added one gallon of muriatic acid in the same-size pool, the reading should drop to around 50 ppm.


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