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

A clean swimming pool relies heavily on clean filter cartridges. The problem is that cartridge filter cleaning methods like the hose do not completely clean the filter. But don't worry, this post shows you how you can easily clean your pool's cartridge filter with muriatic acid.

Let's dive.

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

How to clean pool cartridge filters with muriatic acid

Cleaning your pool's cartridge filter with hydrochloric acid is done as follows:

  1. Turn off the pool pump
  2. Open filter case (release pressure first) and remove 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 an in-depth guide on using acid to clean your pool's filter cartridges.

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

What clogs cartridge filters?

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

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

Another thing that clogs cartridge filters is DE (diatomaceous earth). Some pool owners have experimented with 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 wash the cartridge filter in hydrochloric acid, you need a few things:

Acid Resistant Luvas

safety glasses

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 spanner (optional)

Cartridge filter replacement (optional)

acid neutralizer

Filter cleaning instructions (detailed version)

Let's work now. Here is the detailed guide on how to clean your pool filter with muriatic acid.

1. Turn off the pool pump

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

Therefore, disconnect the power cord or turn off the pool pump at the circuit breaker.

2. Open the filter case and remove the filter cartridge

The next step is to open the filter case to access the cartridge filter.

Before doing this, you must open (or bleed) the bleed valve to release air pressure in the filter case. There is usually too much pressure in the filter case. If you open the tank directly without emptying it, the cap may come off and cause injury. So first release the pressure.

The filter box is usually covered with a lid and this lid is secured with an O-ring or a metal clamp secured with screws.

(Video) How To Acid Clean Your Cartridge Filters

If your pool has a gasket, follow the owner's manual instructions for opening it. Most retaining ring clamps can be opened by pressing the release tab and turning the locking knob to the left (or counterclockwise).

If the filter tank cover is secured 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 remove 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 acidic content makes the elements very aggressive and can damage the cartridge filter.

The acid is also strong enough to cause health problems. Be sure to wear safety glasses, wear long-sleeved clothing, andAcid Resistant Luvas.

Mix muriatic acid with water in a garbage can to dilute the acid. A safe formula for cleaning pool filters is to mix hydrochloric acid and water in a 1:20 ratio. This means that you must 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 the pool filter. Cyanuric acid and hydrochloric acid are very different. We have another article that explains thatDifference between cyanuric acid and hydrochloric acid.

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

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

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

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

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

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

(Video) How To Acid Wash A Cartridge Filter

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

5. Rinse and reinsert the cartridge filter

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

Then check the cartridge filter for damage. If the cartridge filter is worn or damaged, it meansIt's time for a replacement.

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

How to Dispose of Hydrochloric Acid Solution

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

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

Now you can dispose of it down the drain if state or local laws allow it.

See our for detailed instructions.another post here.

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

Cleaning a pool filter with acid is safe. It should only be done twice a year. The acid is strong and will break down 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 muriatic acid cartridge filters, 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 down your pool's cartridge filter every month to ensure maximum performance and durability of the filter elements. The filter(s) should be sprayed down 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.


Your pool's cartridge filter traps a lot of dirt in the water. Algae, leaves, hair products, body oils and food particles are among the few contaminants your filter elements trap in the water. Over time, these contaminants build up on the filter elements and need to be cleaned.

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

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

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

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

You can tell when to clean your pool cartridge filter by checking the filter pressure gauge. The ideal filter pressure for a swimming 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 Your Pool Cartridge Filter (Using Hydrochloric Acid) (3)

You should also clean it after heavy rain, lots of bathing or after an algae infestation.

Can you backwash a pool cartridge filter?

Pool cartridge filters should not be washed as this can damage the filter elements. Backwashing the filter elements also doesn't clean the filter very well. This is because some dirt is deeply embedded in the filter elements and cannot be removed with just the hose.

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

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

You can dip 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. Simply mix muriatic acid with water in the right proportion and dip the cartridge filters into the solution. Give it a try and you'll be amazed at how well it works.

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

(Video) 4 Ways To Clean Your Pool Cartridge Filter


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.

How do you clean algae out of a pool filter cartridge? ›

If the filter cartridge has a coating of Algae, calcium carbonate (residue from calcium hypochlorite), iron or any other minerals, soak the filter cartridge in a solution of one part muriatic acid to twenty parts water until the bubbling stops. RINSE THOROUGHLY AFTER.

How do you clean pool with hydrochloric acid? ›

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.

How much acid do you need to acid wash a pool? ›

10-20 gallons of acid, depending on pool size and severity of staining. Soda Ash to neutralize acid, 2 lbs for each gallon of acid used. Safety goggles and acid safety mask. Screwdriver to remove main drain.

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.

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.

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.

What can I soak my pool filter cartridge in? ›

Overnight soaking

Fill the container with warm water and 1 cup of Cascade complete dishwasher detergent (The Sams club stuff works well too). There are pool cartridge filter cleaners available for sale, but I don't think they do any better job. Let the filter soak overnight (or more if possible) before cleaning.

How do you chemically clean a pool filter? ›

Use a 5-gallon bucket, and make sure the cartridge is completely covered with the water and cleaning solution. Alternatively, you can dilute one part muriatic acid to 20 parts water in a 5-gallon bucket. Place the filters in the bucket and allow them to soak overnight. Check the O-ring on the filter tank.

Can I use Simple Green to clean my pool cartridge filter? ›

Simple Green All-Purpose Cleaner is aggressive on heavy soils and greasy residue, but gentle enough to clean filters without harming the material. The biodegradable* formula won't leave behind harmful residue to circulate into your pool water.

Is hydrochloric acid stronger than muriatic acid? ›

Hydrochloric acid is a purer and more toxic form of muriatic acid. Hydrochloric acid has a normal pH of 1.5 to 3.5, while muriatic acid has a pH of about 1 to 2. Muriatic acid is also less potent because it's diluted with water (usually around 31.5 percent HCl) and contains impurities like iron.

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. It is a component of the gastric acid in the digestive systems of most animal species, including humans.

Can you mix hydrochloric acid with water? ›

Hydrochloric acid (HCl) is very soluble in water and is efficiently removed by rain in the troposphere.

Can too much acid hurt a pool? ›

Simply put, if your pool water is too acidic it can corrode your pool equipment, cause etching on surface materials and cause skin, eye and nose irritations on swimmers. If your pool water is too alkaline, it can cause scaling on your pool's surface and plumbing equipment, and can cloud the pool water.

How long does it take for acid to work in pool? ›

It will take 24 hours for the muriatic acid to react with the existing balanced pool water. Remember never to pour muriatic acid into your pool. Dilute part of the muriatic acid in a bucket of balanced pool water, and then pour it into your pool.

How much muriatic acid can you put in a pool at one time? ›

Using Muriatic Acid as a pH Reducer

For an average-sized pool (think 15,000 to 20,000 gallons), you'll need about a quart of muriatic acid. If your pool is much larger or much smaller than average, you should check with your pool professional.

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 chemical is used to acid wash a pool? ›

Pool acid washing is a process where chemicals—mainly hydrochloric acid, also known as muriatic acid—are combined with water and are sprayed onto your pool's surface to remove any grime and build-up.


1. Acid Washing Your Cartridge Filters
(Pristine Pools)
2. How to Acid Wash a Cartridge Filter for Pool
3. How to clean a cartridge filter element or cartridge. Swimming Pool or Spa.
(Mark's reviews and tutorials)
4. How To Clean Your POOL FILTER (Cartridge, Sand, D.E.) | Swim University
(Swim University)
5. How to Clean a Cartridge Filter
(Swimming Pool Science)
6. 🚫Don't use a Pressure cleaner on your Pool or Spa cartridge. How to clean, what chemicals to use.
(Mark's reviews and tutorials)


Top Articles
Latest Posts
Article information

Author: Francesca Jacobs Ret

Last Updated: 11/15/2023

Views: 5435

Rating: 4.8 / 5 (48 voted)

Reviews: 87% of readers found this page helpful

Author information

Name: Francesca Jacobs Ret

Birthday: 1996-12-09

Address: Apt. 141 1406 Mitch Summit, New Teganshire, UT 82655-0699

Phone: +2296092334654

Job: Technology Architect

Hobby: Snowboarding, Scouting, Foreign language learning, Dowsing, Baton twirling, Sculpting, Cabaret

Introduction: My name is Francesca Jacobs Ret, I am a innocent, super, beautiful, charming, lucky, gentle, clever person who loves writing and wants to share my knowledge and understanding with you.