Clear cloudy pool water by first testing and balancing your chemistry (pH 7.4-7.6, proper chlorine levels), then running your filter 24/7 while adding liquid chlorine to shock level until water clears completely.
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Cloudy pool water is one of the most common pool problems, but it's completely fixable with the right approach. Cloudiness occurs when tiny particles suspended in your water scatter light, creating that milky or hazy appearance. These particles can be dead algae, bacteria, oils, lotions, or chemical precipitates from unbalanced water chemistry.
The key to clearing cloudy water is addressing both the root cause and the symptoms simultaneously. This means balancing your water chemistry while physically removing the particles through proper filtration and circulation.
Before adding any chemicals, you need to know exactly what you're working with. Use a reliable test kit like the Taylor K-2006C to measure:
Write down all your readings - you'll need them to calculate proper chemical doses.
Chemistry balance is crucial because chlorine doesn't work effectively in unbalanced water, and imbalanced water can actually cause cloudiness.
If your pH is above 7.6, add muriatic acid. For a 20,000-gallon pool, start with 1 quart of muriatic acid to lower pH by about 0.2 points. Always add acid to water, never water to acid, and pour slowly into the deep end with the pump running.
If pH is below 7.2, add sodium carbonate (soda ash). Use about 6 ounces per 10,000 gallons to raise pH by 0.2 points.
If TA is too high (above 120 ppm), use muriatic acid added slowly to the deep end. If too low (below 60 ppm), add sodium bicarbonate at a rate of 1.5 pounds per 10,000 gallons to raise TA by 10 ppm.
SLAM (Shock Level And Maintain) is the most effective method for clearing cloudy water. This involves raising your free chlorine to shock level based on your CYA reading and maintaining it there until the water clears.
Use the FC/CYA chart to determine your shock level:
Add liquid chlorine (sodium hypochlorite) - never use cal-hypo shock or dichlor as these add unwanted chemicals. For each 1 ppm FC increase in a 20,000-gallon pool, add approximately 1/2 gallon of 12.5% liquid chlorine.
Your filter is your primary weapon against cloudiness. Run your pump and filter 24/7 until the water clears completely. This isn't the time to worry about electricity costs - stopping filtration will extend the clearing process significantly.
Clean your filter thoroughly before starting. For cartridge filters, remove and hose off debris, then soak in filter cleaner overnight. For sand filters, perform a thorough backwash. For DE filters, backwash and add fresh DE powder.
Brush your pool walls and floor daily to prevent particles from settling and to keep them suspended so your filter can remove them.
Test your FC level every few hours initially, then twice daily. The chlorine will drop as it kills bacteria and oxidizes contaminants. Add more liquid chlorine as needed to maintain shock level.
Critical point: Don't reduce chlorine levels until your water is completely clear and you pass the overnight chlorine loss test (FC drops less than 1 ppm overnight with the pump off).
If SLAM and proper filtration aren't clearing your water after 3-4 days, consider a clarifier. Clarifiers bind tiny particles together so your filter can catch them more easily. Use 1 ounce per 5,000 gallons of water and run your filter continuously.
For severe cloudiness, flocculant might be necessary. Floc causes particles to clump and settle to the bottom where you can vacuum them out. However, this requires vacuuming to waste, which means adding fresh water afterward.
If your cloudy water has any green, yellow, or pink tint, you're dealing with algae, not just cloudiness. Continue the SLAM process but expect it to take longer - possibly 5-10 days depending on the severity.
Once your water is clear, prevent future cloudiness by:
Safety Warning: Always handle pool chemicals with care. Wear protective equipment, never mix different chemicals, and store them in a cool, dry place away from children and pets.
Most pools clear within 2-5 days using this method. If your water isn't showing improvement after a week of consistent treatment, consider having your water professionally tested to check for unusual chemical imbalances or equipment problems.
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