How to Clear Cloudy Water in a Swimming Pool

A chlorine shock will clear cloudy water in your pool.

Cloudy pool water can be caused when the free chlorine level drops below 1.0 parts per million (ppm) or after a heavy rain. The ideal chlorine level is 2.0 to 3.0 ppm. The extra water in the pool and in some regions, the acid rain will lower the available chlorine causing bacteria, algae and living organisms to multiply. When you see that the water is turning cloudy, you will need to add the correct chemical and clear up the pool water before it gets out of control, which could take days to clear.

Things You'll Need

• Shock (sodium hypochlorite)
• Chlorine test strip
• pH test strip

Instructions

1. Turn on the pool filter at dusk. Set the filter to run for at least eight hours or until the next morning.

2. Use 2 gallons of sodium hypochlorite to raise the chlorine level 10 ppm in a pool with 20,000 gallons of water or 4 gallons of chlorine for 25,000-gallon pool.

3. Pour the liquid chlorine in the deep end of the pool and let the pump filter the water all night.

4. Assuming the water is cleared up the next day. Test the pH and chlorine levels in the pool using a chlorine test strip and pH test strip. Sodium hypochlorite will raise the pH in the pool to an unsafe level and the pH will need to be lowered.

Tips & Warnings

• If you need to backwash the pool after shocking, you will need to check the chlorine level again and add more shock. Backwashing removes water from the pool, which takes the chlorine along with it.

• If you add water to the pool, check the chlorine level and add chlorine to keep the chlorine in range.

References

• Pool Manual: Chlorine
• North Carolina Department of Environmental Health Services: Water Chemistry for Swimming Pools