How to Clear Cloudy Pool Water

By: Chris Deziel

When your swimming pool is properly maintained, you should be able to see features on the bottom clearly, even at the deep end. There is a whole list of reasons why pool water can turn cloudy, but they basically boil down to improper maintenance, heavy usage and environmental conditions, such as intense sun, debris from trees and birds and pool algae. Clearing a cloudy pool usually takes time, although there is a faster -- if somewhat troublesome -- way of doing it.

Pool Maintenance Issues

  • Insufficient operation of the pool filter -- Your pool water may have turned cloudy simply because you don't run the filtration system often enough. It should be working for at least eight to 10 hours a day -- check the manufacturer's specifications for your particular system. 
  • Failure to backwash -- If you run the filtration system often enough, the filter itself may be clogged with debris. It's important to backwash the filter regularly by reversing water flow through the system -- check your manual for the proper way to do this.
  • The pH is too high or too low -- It's important to check the pH of the water regularly with test strips; it should be between 7.2 and 7.6, and the total alkalinity should be between 80 and 125 parts per million. Add a product to raise pH or another to lower it, as needed. Add a separate product to increase alkalinity. 
  • Not enough sanitizer -- Most pools require regular addition of chlorine, bromine or other minerals to control algae and other microorganisms that can cloud the water. Saltwater pools have a generator that converts salt in the water to chlorine. Even if you add chemicals regularly, you must periodically shock the water to oxidize them and render them potent.

Clearing Cloudiness Quickly

If you've been maintaining your pool improperly, correcting your maintenance habits will probably clear up the water, but it may take several days to a week. There are three ways to get faster results:

Stir Up the Water and Skim and Drain

Small particles tend to stay suspended in the water, and some may even sink to the bottom, only to be recirculated when someone jumps in the pool. You can remove many of these particles simply by agitating the water with a stick or brush, or simply by swimming, then allowing the pool's skimmer to remove the particles from the top of the water. Also turn on the bottom drains to pull out particles near the bottom of the pool. This can be time-consuming, but it doesn't involve adding more chemicals to your pool water.

Use a Water Clarifier

Water clarifiers are coagulants -- they surround small particles with a membrane that allows the particles to stick together and form larger ones, and eventually these particles are removed by the pool filter. If cloudiness is a problem, add a clarifier every week, but do not exceed the recommended dosage -- overdoing it may actually make the cloudiness worse.

Floc the Pool

A pool flocculant works in the same way as a clarifier, but it's a stronger chemical that actually causes the particles to sink to the bottom, and you have to remove them physically with a pool vacuum. Flocking the pool is the fastest way to get rid of severe cloudiness, but a specific procedure is required:

Step 1

Turn off your pool's filtration system by setting the pump to "Recirculate." This prevents the particles from clogging the filter.

Step 2

Prepare the floc by adding it to a bucket of water according to the instructions on the container. Disperse it in the pool and allow the water to recirculate for five to six hours.

Step 3

Turn off the pool pump and allow the sediment to sink to the bottom. This may take two or three days.

Step 4

Set the pump to "Waste," attach a pool vacuum and vacuum the sediment from the bottom of the pool. You'll lose a lot of water during this procedure, so you may want to keep a hose running in the pool while you're vacuuming.