Cloudy pool water: tips to make your swimming pool crystal clear again

Need to learn how to clear cloudy pool water, fast? We explain what causes it and how to fix it

luxury swimming pool with loungers and parasol
(Image credit: Vyacheslav Lopatin/Alamy Stock Photo)

Cloudy pool water can instantly make a swim seem less inviting. And on those hot summer days, you won't want to miss out, so you'll need to know how to get your water sparkling clean again.

The good news is, it's usually pretty simple to get the water in your backyard pool cleared up and looking pristine. With our tips, you'll be able to cool off outdoors in no time, not to mention, throw epic pool parties that everyone will want to attend.

4 common reasons for cloudy pool water

Knowing what causes cloudy pool water can help you prevent it in the first place.

1. Problems with your pool's filter

One of the most common reasons for cloudy pool water is a problem with your pool's filter. If it's not working properly, it won't be able to clear contaminants from your pool effectively. This is why checking and cleaning your filters – and replacing them when necessary – should be a crucial part of your pool maintenance routine. Remember to clear out skimmer baskets frequently, too. 

According to Swim University (opens in new tab), you should also make sure your filter is on for long enough each day for the entire pool's worth of water to pass through it – this will usually take at least eight to 12 hours. 

leaves in swimming pool skimmer basket

Clear out debris from your pool's skimmer basket regularly

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2. Unbalanced pool chemicals

Another reason for cloudy pool water is unbalanced chemical levels. This includes your chlorine levels and the pH and alkalinity. Test the water often, adjusting the levels with chemicals accordingly, so that contaminants can be dealt with effectively. It's particularly wise to do this after heavy use, such as a pool party

Shocking a pool, just as with shocking a hot tub, should also be part of your regular routine for an extra boost of sanitation and to keep your water looking clean and clear. Cloudy pool water after shocking may occur, but it's generally just a temporary reaction and will clear up as the filter runs. You can find our pick of the best pool shocks in our buying guide.

testing chemical balance in swimming pool

Test your pool to ensure an optimal chemical balance

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3. Rainwater affecting your pool's water

You may also notice cloudy pool water after rain. As Swim University explains, this is because the excess water will dilute the chlorine levels in your pool, making it less effective at dealing with bacteria. Rainwater run-off from your pool patio or deck can also introduce an influx of contaminants. 

Again, you'll need to test and adjust the chemistry of your pool accordingly, as well as clean out any debris that may have blown into the pool during the storm.

lifebelt in swimming pool in rain

Inclement weather can cause a pool to turn cloudy

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4. Algae build-up

If you've noticed your pool turning green as well as cloudy, pool algae is likely to be the cause. This is a common problem but can be dealt with by giving it a thorough deep clean (although milder cases can be treated with an algaecide).

green algae in swimming pool

Pool algae can turn the water green

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How to get rid of cloudy pool water quickly with a clarifier or flocculant

The bottom line when it comes to preventing cloudy water is to keep up a proper pool maintenance routine, taking on board all the tips above. But if you need to know how to clear cloudy pool water fast, you're in luck: there are a couple of different methods that will give your water its sparkle back within just a few days.

The first approach is using a pool clarifier, available on Amazon (opens in new tab). These make the pathogens in your pool clump together, making it easier for your pool's filter to clear them out. Clean your pool first, using a pool brush, then follow your chosen product's application instructions. Remember to keep the filters running until the water is clear again – this can take around three days.

Alternatively, you can use a pool flocculant, also found on Amazon (opens in new tab). As Swim University says, this is more suited for extremely cloudy water. Like a clarifier, it also clumps together contaminants, but it makes them sink to the floor of your pool. You'll then need to hoover them up with a manual pool vacuum, set to the waste setting. Keep water levels topped up with a garden hose as you carry out the job. This method requires more work on your behalf, but it should clear your pool quickly – usually in one to two days.

family in swimming pool

Keep your pool water clear for a fun and safe swimming experience for all the family

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Holly Crossley
Holly Crossley

The garden was always a big part of Holly's life growing up, as was the surrounding New Forest where she lived. Her appreciation for the great outdoors has only grown since then. She's been an allotment keeper, a professional gardener, and a botanical illustrator – plants are her passion.