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How to Clear up a Cloudy Blue-Green Swimming Pool

By Daniella Lauren

Maintaining a swimming pool requires you to be on the lookout for some pretty significant water problems. One common problem can be the appearance of cloudy blue-green water, which typically means that you have algae growing in your pool’s water. Fortunately, you can address this issue with regular pool chemicals and a little extra effort. After correcting the issue, you will need to check on the pool on a regular basis to ensure that your water does not experience this problem again.

Test your pool’s water with the at-home testing kit. This will help you determine what chemicals need to be added to the water and in what amounts.

Add chlorine, a pH increaser and a calcium increaser as recommended to return the water to its proper condition. The water's pH balance should fall between 7.2 and 7.8, its alkalinity from 80 to 100 and its calcium hardness from 150 to 300 ppm.

Brush the inside of the pool to release any algae from the sides and bottom of the pool.

Run the pool filter at least eight to 10 hours each day to help remove algae. You can also backwash the filter to ensure that the water runs clear.

Increase the water level in the pool. Backwashing will release dirty water from the pool; you will need to ensure that the water does not fall any lower than 2 inches from the bottom of the skimmer.

Add shock to the pool to increase the pool's chlorine to 10 times the normal level. Shock is a super-chlorinated chemical used to kill algae and bacterial growth in the pool water. Normal chlorine levels range from 1.5 to 3.0 ppm.

Vacuum any algae from the bottom of the pool. You should also continue to run the filter eight to 10 hours a day after vacuuming up the algae in the pool.


Things You Will Need

  • At-home water test kit
  • Chlorine
  • pH increaser
  • Calcium increaser
  • Soft-bristled pool brush
  • Pool shock


  • You can use the pool once the water is a natural, clear blue color. Chlorine levels should be around 3.0 ppm before you swim in the pool.

About the Author


Daniella Lauren has worked with eHow and various new media sites as a freelance writer since 2009. Her work covers topics in education, business, and home and garden. Daniella holds a Master of Science in elementary education and a Bachelor of Arts in history from Pensacola Christian College.