My Pool Water Is Cloudy After Adding Chlorine & Algaecide

Learning proper pool chemistry is not difficult, but occasionally chemicals get out of balance, causing algae growth, suspension of metals in the water and cloudiness. Cloudiness can occur from a number of factors that are easily corrected with a little attention. If your pool water becomes cloudy after adding chlorine or algaecide, redouble your efforts to restore the right pH and calcium hardness levels in the pool and take special care with your pool filter.

The right balance of pool chemicals and filtering will keep pool water from becoming cloudy.

Adjust pH Level

If the pool water's pH is too high, chlorine sanitizer will work more slowly, according to the website Par Pool & Spa. This will, in turn, favor the growth of bacteria and algae that can cloud the water. High pH can also contribute to formation of scale and cause cloudiness. The recommended pH level for swimming pools is 7.4 to 7.6. To raise pH and make the water more alkaline, add sodium carbonate. Add muriatic acid to lower pH and make the water more acidic.

Proper Chlorine Level

Allowing the chlorine level of your pool to get too low can also cause cloudy water. To correct this, add chlorine to shock the pool and run the filter continuously until the water clears. The standard amount of chlorine required to shock a 10,000-gallon pool is 1 gallon of liquid chlorine or 1 lb. of granular chlorine, according to Pool Info. Resist adding clarifier, which can cause the water to remain cloudy. Add 2 oz. of algaecide for each 5,000 gallons of water in your pool every two weeks, then add shock.

Too Much Calcium

Too much calcium in pool water can also cause problems. A high calcium residue can occur on the water's surface as well as in the filter, pipes and other plumbing. The recommended level of calcium hardness is 200 to 400 parts per million (ppm). To reduce calcium hardness, Pool Wizard recommends using commercial water hardness reducers or chelating agents to maintain calcium suspension in the water.


Metals can also contribute to the cloudiness of water. Even algaecides can make pool water cloudier instead of cleaning it, because they often contain copper, a metal that can suspend in the water. A metal chelating agent added to the water will help to keep these particles in suspension until they are filtered out of the water.

Algae Growth

Algae growth can make pool water cloudy and odorous. To remove the algae, you must shock the pool. This means using 10 times the amount of chlorine you ordinarily use. Using an algaecide helps to remove the outer cellular walls of the algae so the chlorine can work against them. You must also filter the pool water continuously for 24 to 48 hours to remove the growth from the water.