How to get rid of white water mold - Sutro, Inc

How to get rid of white water mold

You walk around your swimming pool and notice small bits of white mucus-looking patches all over the surface of the water and maybe even on the pool walls.

It looks like your pool has caught a common cold!

Perhaps calling it "a cold" would be too assertive or sarcastic, but the fact is that your pool water needs immediate treatment because it has been infested with white water mold

The growth of white water mold is a common occurrence in swimming pools regardless of their size.

Read on to understand the nuances and how to get rid of white water mold in the pool

What is white water mold? 

White water mold is a type of fungus. So technically, it is a microorganism that feeds on organic matter like decomposing leaves and debris in your water. 

Another microorganism that often accompanies white water mold is pink slime. It is a type of bacteria (not algae, as people usually believe) that generally thrives on top of the water. 

What does white water mold look like?

White water mold looks like shreds of white tissue paper floating over the surface of pool water.

This mold can also deposit in moisture-heavy places like shower heads, bathroom walls, pool corners, etc.

White water mold loves PVC and plastic materials, so it is common to find it on pool equipment or hoses. 

Its occasional companion, the pink slime, looks pink or slightly red and is often referred to as pink algae.

Like water mold, it is also found in hard-to-reach places like tile crevices, corners, skimmers, and behind return jets. 

Why is there White water mold in the pool?

As already mentioned, white water mold is a part of the natural ecosystem and mainly occurs on its own.

However, some other factors also contribute to it.

For example, a garden hose used to fill the pool with water can have water mold already built up in it, and you can transfer it when you top off your pool. 

Similarly, an unclean and clogged pool water filtration system also contributes to the growth of white water mold in pools. 

A common misconception is that the use of biguanide (also known by the brand name bacquasil) contributes to the infestation of mold in a pool.

If you don’t already know, biguanide is a pool sanitizer used instead of chlorine or bromine to shock the pool

Another cause of mold in the pool is the failure to maintain proper sanitizer levels. 

Why is white water mold a problem? 

First of all, the presence of white water mold in your pool makes it look pathetic and gives an impression of your carelessness towards hygiene.

If left untreated for longer durations, this mold will end up clogging the filtration system of your pool.

The mold will also use up your sanitizer, and that will cause unsanitary water or algae blooms. 

Is white water mold harmful to humans or animals?

Water mold itself is not that big of a problem for us humans.

That’s because there are many types of molds that we regularly ingest through the air, water, and food.

Only people allergic to mold will face mild health issues when they come in contact with white water mold. 

However, its accompanying partner, pink slime, is a significant threat to human health, as exposure can result in respiratory issues, urinary tract infections, and more.

As far as animals are concerned, white water mold does affect them and can cause serious health problems with prolonged exposure.

How to get rid of white water mold in a pool

Before you start, you must also remember that water mold is resistant to certain commonly used chemicals.

Chlorine and biguanide are the most commonly used sanitizers for pools. Treating white water mold in a chlorine pool is slightly different than in a biguanide pool.

Additionally, treating pink slime has another procedure, but that is a topic for another discussion. 

How to treat white water mold in a chlorine pool

Make sure you follow these steps thoroughly because white water mold is stubborn and it will return soon if not treated properly. Here are the steps to treat it in a chlorine pool

  1. Clean the filtration system.
    If your pool has mold, it is evident that your filtration system also has it because of water circulation.

    The first step is to clean your D.E or sand filter through backwashing or using a chemical cleaner.

    Otherwise, you may also use a clean hose to rinse your filter cartridges thoroughly. 
  1. Correct the pH level.
    Bring the pH of the water in the 7.2 to 7.6 range. You can use our guide to increase or decrease the pH. 
  1. Shock the pool.
    This will not be a regular shock, but one with three or four times more powder than usual for a hard shock.

    That’s because white water mold is resistant to chlorine and requires a harder punch.

    Always shock your pool at dusk or night to prevent the sun's rays from lowering your chlorine’s effectiveness and to get the maximum benefit.
  1. Scrub, Pump, and Scrub.
    Grab appropriate protective gear and a pool brush, and start scrubbing the pool to loosen up any mold.

    Pay special attention to corners and spots like the skimmer, ladder, stairs, and around return jets.

    Once complete, run the pump for a full 24 hours to allow the filters to catch the loosened mold. Repeat this process once more for the best results.
  1. Vacuum the pool.
    Use a pool vacuum cleaner to get rid of any mold that may have settled down to the bottom.

    This is an important step to ensure the proper elimination of any residual mold.
  1. Clean the filter.
    Since the water was under circulation, some residual mold might have made it up to the filters. So give the filtration system a thorough cleaning again. 
  1. Test and balance.
    The final step is to test the water and adjust the chemistry.

    An easy way to do this is by using our Sutro Pool Monitor, which will give you regular and accurate updates on your mobile app.

    Do not use the pool until the levels return to normal.

How to treat white water mold in a biguanide pool

Follow these steps to clean white water mold from your biguanide pool:

  1. Clean the filtration system. 
  1. Balance the water chemistry.
  1. Thoroughly brush the pool’s floor and walls.
  1. Run the pump for 24 hours, and brush the pool again.
  1. Vacuum the pool.
  1. Clean the filtration system again.
  1. Balance the water chemistry.
  1. After five to seven days, add four ounces of biguanide algaecide for every 10,000 gallons of water in your pool.

How to prevent white water mold?

The best method to prevent mold from entering or growing inside your pool is to perform regular maintenance.

Since mold is a naturally occurring fungus, there’s little you can do to avoid it completely. Here are the steps you must take to prevent it: 

  • Brush your pool regularly and keep it clean.
  • Run the water filtration system regularly.
  • Conduct a thorough cleaning before opening the pool.
  • Allow regular sunlight to hit the water if you use covers on an outdoor pool.
  • Keep your pool tools and equipment clean.
  • Keep the water chemistry balanced at all times with the right pool chemicals.


The build-up of white water mold in a pool is a natural occurrence, but it can be avoided with regular pool maintenance and proper water chemistry.

The process to eliminate mold is slightly different for chlorine pools and biguanide pools, and it is time-consuming.

So the best course of action is to prevent it from infesting the pool. 


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