How to Get Rid of White Water Mold and Pink Slime in Your Pool

Written by Michael Dean
March 27, 2024

white water mold and pink slime in a swimming pool

If you’ve noticed little bits of white, mucousy material floating in the water, you likely have a white water mold issue. Sometimes, along with that white mucus-like substance, you may also notice bits of pink slime.

I know this combination sounds sickening, like literal cold symptoms, but it happens pretty frequently. Fortunately, there are ways you can quickly remedy this, and there are precautions you can take to prevent it from happening again. Below, I cover those topics and more common questions about getting rid of pink slime and white water mold in your swimming pool.

Main Takeaways

  • If there is a white film layer on the surface of the water, you may be dealing with white mold. It is a fungus-like organism that thrives in moist environments.
  • Pink slime resembles algae but is instead an airborne bacteria that can cause infections like UTIs.
  • White mold or pink slime may be in your pool because your filtration system may be blocked, clogged, or stopped or because of unbalanced water.
  • To get rid of white mold, you must triple or quadruple shock the pool. And to get rid of pink slime, add a pink bacteria cleaner and triple and quadruple shock the pool.

What is White Water Mold?

A surefire way to tell if your pool is bogged down with white water mold is the white film layer on the surface of your water. Many people describe this film as a layer of ripped tissue paper; it looks like shreds of thin paper that float around and cloud your water.

White water mold is naturally occurring and can happen in any pool. It’s a fungus-like organism, and its scientific name is Oomycota.

white water mold in a swimming pool

Mold serves a critical role in nature — it helps break down nutrients and substances as they decay. It thrives in moisture-rich environments, and for that reason, it’s drawn to your pool area.

Experts note that people are “exposed to mold every day,” and it’s often harmless in minute amounts. However, white water mold can be an irritant for people if you’re exposed to it frequently or in large quantities, especially if you suffer from mold allergies. To keep you and your family healthy, regularly checking, preventing, and cleaning your pool of white water mold is crucial.

What is the Pink Slime in Your Pool?

A substance that can go hand-in-hand with white water mold is pink slime. It’s called Serratia marcescens, and it’s drawn to moist environments, just like white water mold.

People often misunderstand pink slime. It strongly resembles algae, and therefore, many mistake it for pink or red algae or even leftover residue from hard water. That is not the case, though.

pink slime in a swimming pool

This pink slime is a form of airborne bacteria. It can cause several forms of infection, like a urinary tract infection, if you ingest the bacteria, get it in your eyes, or are exposed to it over long periods.

Fortunately, it’s easy to spot pink slime. It has a pink or red coloring that makes it highly visible. You may find it in tile crevices, on your shower curtain liners, and in hard-to-reach places. Pool filters are common pink slime hot spots, and the walls of your pool may sport a pink residue from time to time too.

As the name implies, while this bacteria typically have an identifiable coloring, it also feels slimy to the touch. While I don’t recommend touching it to test it— if you have noticed mucky substances in your pool, it could be an indicator of bacteria.

Any damp, wet area is susceptible to bacteria growth. Your pool is, unfortunately, an excellent breeding ground for pink slime.

What Causes White Water Mold and Pink Slime?

When white water mold and pink slime grow, there’s almost a domino effect. While it may start in small amounts, it quickly multiplies until there’s a full colony.

There are several reasons why white water mold or pink slime could be popping up in your pool. It could be an indicator of poor circulation. Your filtration system may be blocked, clogged, or stopped.

If your filter experiences any interruption, that stagnant water could welcome mold growth. When white water mold and pink slime grow, it often builds up layer after layer of microorganisms. Filtered and flowing water help prevent the bacteria from layering.

Another cause of white water mold and pink slime is unbalanced water. If you lack proper chlorine or biguanide levels, you may unwittingly be building up groups of mold and germs.

As I mentioned, both of these substances are naturally occurring. You’ll find them in stagnant bodies of water practically everywhere. To keep you safe and your pool swim-ready, I want to help you understand how to treat and prevent these microorganisms from growing.

If You Have a Chlorine Pool…

Unfortunately, not even a chemical as powerful as chlorine could fully protect your pool from white water mold or pink slime. White water mold is often resistant to chlorine.

Chlorine is typically an excellent line of defense against bacteria. To clean your chlorine pool, it may just take a few rounds of shocking and balancing your water.

How to Get Rid of White Water Mold

White water mold can be a bit tricky to clean. Its resistance to many pool sanitizers, like chlorine, means your pool will likely require a careful eye and thorough scrubbing.

To be sure you’ve removed every bit of mold spores or colony growth, there are several steps to follow.

Step 1: Double-Check the Pool Pump

One of the biggest causes of mold growth is poorly filtered water. The first thing you should do is check that your pool’s pump and filter are working correctly.

Until your pump and filter are in good working order, you won’t be able to stop and prevent white water mold growth entirely.

Step 2: Skim the Surface of Your Pool

If you have a water mold infestation in your pool, it’s probably already visible on the surface.

To get an exact look at your pool, skim the water’s surface and try to remove as much of the mold as possible. Throw the debris away and make sure your skimmer is clean.

Step 3: Clean the Filter

After checking that your filtration system is still working, it’s safe to assume that your pool filters have trapped mold and you need to clean your filter.

If you have a sand filter, you may need to backwash the system to clean it properly.

If you have a cartridge filter, one of the simplest ways to clean it is with a hose. You can also use a filter cleaner if it’s incredibly moldy.

Step 4: Balance the Water

Check on the balance of your water now. It should have a pH of 7.2 to 7.6. Any water that is too acidic or too alkaline could impact your chlorine. The chemical may not be able to fight off bacteria properly if the water is unbalanced.

Step 5: Shock the Pool

To destroy the water’s unwanted substances, you’ll need to fully and thoroughly shock the water. You may need to treat it three or four times over.

The key here is that you’ll have to know precisely how much water is in your pool to shock it effectively. For every 10,000 gallons of water, you’ll need to add about three to four pounds of calcium hypochlorite.

In The Swim Calcium Hypochlorite Chlorine Granular Pool Shock

In The Swim has a reliable cal hypo shock that is effective and easy to use.

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Keep in mind; this is well above the average chlorine level for your pool. The chemical product you use to shock your water should have some indication in its instructions on when it’s safe to swim again.

Step 6: Scrub it

You’ve shocked the water; now it’s time to scrub!

Be sure to wear some protective gear, like gloves, so you don’t get chemicals on your skin. Using a solid, firm brush, scrub the bottom, sides, and hard-to-reach spots all around the pool. Scrub the steps and the ladder, and check your skimmer. Any underwater area is fair game for mold, so wholly and thoroughly wipe it all down.

Step 7: Run the Filtration System

To filter the gunk out of your pool, run the pool pump for a full 24 hours.

The proper circulation will help separate and remove the mold floating in your water.

Step 8: Continue Cleaning the Pool

Even the tiniest bits of mold can multiply into massive infestations. By scrubbing your pool thoroughly a second time, you significantly increase your chances of removing all the mold.

Step 9: Manually Vacuum the Pool

After at least two scrubs, there’s likely some floating debris, residue, and remaining mold that has settled on the bottom of your pool— vacuum along the bottom to remove whatever substances are left over.

Step 10: Clean the Filter Again

One of the last steps needed to get your pool back in tip-top shape is to clean the filter one final time.

Thoroughly wash the cartridge filter, sand filter, or D.E. filter with a cleaner product.

Step 11: Test the pH of the Water

The pH levels should be in the correct range, and the chlorine levels should be back to normal before anyone considers getting back into the pool water.

For the next few days, continue to run the pump frequently, scrub the sides, and vacuum the base. You want to keep a close eye out for any signs of mold. By thoroughly watching and cleaning your pool, you’ll help stop the mold in its tracks and prevent it from returning.

How to Get Rid of Pink Slime

Like white water mold, pink slime is also resistant to pool chemicals. It will take a complete shock and cleaning to rid your water of pink bacteria altogether.

Step 1: Clean the Pool and Filter

To start, check and clean the pool filter. It’s safe to assume that if pink slime is visible around your pool, it’s also in the filter.

Give the sides and base of your pool a good scrub with a firm brush. Like mold, this bacteria also lurks in hard-to-reach places, like under ladder handles and on your tiles.

Step 2: Balance the Water

Check the pH levels of your water and balance it as needed. The pH levels should be between 7.2 and 7.6.

Step 3: Shut Down the Pump

For the pool to properly soak the chemical treatment in, you need to shut off the pump, so the water becomes stagnant.

Step 4: Add a Pink Bacteria Cleaner

Search for a cleaner or algaecide that specifically kills and treats pink slime or pink bacteria. Closely follow your product’s instructions to determine how much you should add based on your pool’s volume.

Step 5: Shock the Water

You’ll need to triple or quadruple shock the pool’s water; it will vary based on the size of your pool and the number of bacteria. I recommend you add three to four pounds of calcium hypochlorite for every 10,000 gallons of water. Let the shocking water set for about 24 hours.

Step 6: Vacuum the Pool and Clean the Filter

After that waiting period, you may need to put on some protective gear, like gloves, and manually vacuum the bottom of your pool. Clean out the remaining debris and bacteria. Thoroughly clean your pool’s filter with a cleaner.

Step 7: Turn the Pump Back On

Now you can turn the filtration system back on and run it as you usually would.

Step 8: Watch the Chlorine Levels

For several days after this treatment, the chlorine must remain at a higher-than-normal level. The average measurement is about three parts per million, and experts recommend raising it to five ppm.

Finally, after several days, you can let the chlorine level back out and correctly balance the pool’s pH measurement.

If You Have a Biguanide Pool…

Biguanide is a chemical alternative to chlorine. If you’re frequently irritated by chlorine, a biguanide pool is a more soothing alternative for your skin.

How to Get Rid of White Water Mold

Cleaning out the white water mold from your biguanide pool is similar to cleaning the mold out of a chlorine pool. You will follow the same steps with only a few notable differences.

To start, you will check the pump, skim the surface, clean the filter, and balance the water. Even the pH level should be similar— around 7.4.

Shocking the Water

The steps vary when it comes time to shock the water. Instead of using a chlorine-chemical shock, you should use an oxidizer shock intended for biguanide pools.

The typical level of biguanide treatment is one gallon of oxidizer for every 10,000 gallons of water. To fully clean out your water, you need about three times that level: three gallons of oxidizing shock treatment for every 10,000 gallons of water.

After shocking the water, you should thoroughly scrub every inch of the pool. Bacteria can lurk in hard-to-reach places. Run the pump for a solid 24 hours to filter all of the gunk out. Then, like a chlorine pool, brush the pool’s sides and bottom a second time and manually vacuum out the remaining debris. Thoroughly clean your filter with a specific filter cleaner.

You should then test and balance the water and monitor the levels for about one week.

Add a Biguanide Algaecide

After about one week of balanced levels, you should add a four-ounce dose of biguanide algaecide for every 10,000 gallons of water in your pool. This action will not only thoroughly treat your water; it will also rigorously rid the area of remaining mold.

Here’s my recommended biguanide-specific algaecide from Baquacil.

Baquacil Performance Algaecide Cleanser
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Like a chlorine pool, closely watch the water for any new white water mold over the next several days. Mold is tricky and can quickly multiply. Hopefully, you will stop the white water mold in its tracks by vigorously scrubbing, shocking, and filtering your water.

How to Get Rid of Pink Slime

Ridding your biguanide pool of pink slime follows very similar steps as a chlorine pool.

To start, clean your filter and thoroughly scrub your pool. You should use a  stiff brush to clean the sides, base, and challenging-to-reach places. Balance the pH of the water to about 7.4 and turn off the pump.

Add a Biguanide Algaecide

Although pink slime is not algae, a biguanide-specific algaecide will help kill unwanted bacteria. After turning off the pump, add this product. Follow the directions on the algaecide to determine how many ounces to add per every 10,000 gallons.

Shock with an Oxidizer

You cannot use a chlorine-based shock product in a biguanide pool. Look for an oxidizer and add about three gallons for every 10,000 gallons of water in your swimming pool.

Check the Sanitizer Level

After adding algaecide and oxidizer to the water, check the biguanide level of your pool. To rid your pool of pink slime confidently, adjust the biguanide level to about 50 parts per million.

Let your pool sit stagnant for about 24 hours. The next day, you should thoroughly vacuum your pool, clean the filter a second time (with cleaner), and check that the biguanide level is still at 50 ppm.

Then you can finally rerun the pump until your water completely clears back to normal. The last step to check before jumping back in is that your water is balanced again to normal levels.

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Tips to Prevent White Water Mold and Pink Slime

Mold and slime are a slippery slope; they can snowball in the right conditions. To stop them from coming back, make sure your pool has substandard conditions for bacteria growth.

Carefully maintain the correct chlorine and biguanide levels, regularly clean the pool, and always double-check that the pump is in working order. This routine cleaning and maintenance will keep your pool in perfect swimming condition. Jump in!

Questions? Shoot me a note.

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