Pool Spa Life
Pool Spa Life

How To Clean Cloudy Pool

Get your pool water clear and sparkling

If your pool water is cloudy, there are several things that could be wrong. It is important to look for the cause before treating cloudy water. If you don’t find the cause, the pool will go cloudy again in a few days and you will have wasted your time.

Check your filtration and circulation system

Is the filter working properly? If the flow isn’t strong enough to push your hand away, you may be having problems with your filter and service may be required.

  • Does the filter need to be backwashed?

  • Are there any blockages or a build-up of debris?

  • Has the filter been chemically cleaned recently?

  • Is there enough sand or DE (Diatomaceous Earth) in the filter?

Ensure your filter is running for up to 12 hours a day depending on the season.

Check the chlorine level

The free chlorine level in the pool should be maintained between 1.0 and 3.0ppm. There are products available that assist your sanitiser by preventing bacteria and algae while removing organic waste build-up, which will help maintain the free chlorine level and reduce incidences of cloudy water. Check if chloramines are present, that is can you smell a very strong chlorine smell?

Check the pH and Total Alkalinity (TA)

The pH needs to be within the range of 7.2 and 7.6 and the TA between 80 and 120ppm. If the water is out of these ranges, it can cause cloudiness and build-up of scale. Your local SPASA pool shop can test all of these elements and make recommendations on how to keep these in balance.

Check for algae

Algae infestation, even in its early stages, can cause cloudy water. Ensure you add a preventative dose of algaecide every week. Algae may not always be visible, you may notice it because stairs, walls or fixtures are sticky or slimy. If the pool is cloudy because of an algae infestation, you will need to undertake a full algae treatment<Link to green pools page>.

Treatments for cloudy pools

After ruling out the above causes, the following treatments can be administered.

  • Adjust pH to 7.2 to 7.6

  • Add a dose of clarifier and run pump until water is clear - this may take 24 hours for a small cartridge filter on an above ground pool. You must run the pump because a clarifier glues particles together so they are big enough for the filter to remove. If you turn off the pump, the particles will fall to the floor and not go into the filter.

  • You can swim 2 hours after adding chemicals to the pool.

  • Adjust pH to 7.2 to 7.6

  • Add a dose of heavy-duty clarifier and run pump until clear - this may be 72 hours for an above ground pool with a small cartridge filter

  • You cannot swim until the water is clear. You may not be able to see if anyone is at the bottom of the pool

  • For a sand filter:

    • Adjust pH to 7.6 to 7.8

    • fill pool to the brim with water

    • turn off the pump

    • turn multiport valve to re-circulate or bypass

    • turn on the pump

    • for a 40,000 to 60,000 litre pool, add 1 litre Liquid Floc

    • run pump for 2 hours

    • turn off pump

    • leave to settle overnight

    • you can also use granular Alum Floc for this, but for every 2 kg you will need to add 4 kg of Buffer, to get the pH right

    • the pool water should now be clear with a layer of sediment on the bottom

    • if not, re-adjust pH to 7.6 to 7.8 and repeat

    • if the water is still not clear, visit your local SPASA pool shop for advice

    • turn off pump

    • turn multiport valve to waste

    • turn on the pump and connect up the pool vacuum (you cannot use a pool cleaner for this) and vacuum sediment to waste

    • watch the pool water level, stop if it reaches the bottom of the weir door and add more water

    • when finished, turn off the pump and turn valve to rinse

    • turn the pump on, run for one minute and turn off

    • turn valve to filter and turn on the pump

  • take a water sample to your pool shop to re-balance the water and test phosphate level

  • add phosphate remover as needed

  • swimming can resume after the water is balanced

  • For a cartridge filter, with a waste line: 

    • Adjust pH to 7.6 to 7.8

    • take out the filter cartridge and continue as per the steps for a sand filter - you may ruin the cartridge if you run filter floc through it

  • For a cartridge filter, without a waste line: 

    • most cartridge filters do not have a waste line, therefore flocking the pool is not an option

    • adjust pH to 7.2 to 7.6

    • add a dose of filter aid to the filter to speed the process

    • add a dose of strong clarifier to the water, every day until it is clear

    • run pump continuously

    • monitor the pressure gauge and clean the filter when necessary

    • it may take 3 or 4 days to clear an above ground pool with a small cartridge filter

  • take a water sample to your pool shop to re-balance the water and test phosphate level

  • add phosphate remover as needed

  • swimming can resume after the water is balanced

Cloudy water can also be a sign that superchlorination is needed

If there is an excessive presence of chloramines, the pool will have a strong smell of chlorine and the water will make eyes sore and/or skin itchy when you get out of the pool. These are all signs that the water may need to be superchlorinated. Another sign is when pool water is hazy after a days’ swimming – caused by a buildup of skin proteins, or high bather load.

  • Add a three times daily dose of Chlorine. Liquid is easiest, 5 litres in a 50,000 litre pool, but use granular if Liquid is not available (360 grams of Calcium Hypochlorite)

  • Adjust pH to 7.2 with acid; the extra Chlorine added will raise the pH, especially Liquid.

  • Leave the salt chlorinator running as normal 

  • Swimming needs to be stopped for 2 hours after adding any chemicals

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