How Long Do Pool Chemicals Take to Work?

How Long Do Pool Chemicals Take to Work?

One of the most important tasks for the owner of a swimming pool is to keep the water chemistry properly balanced. This ensures that the water remains clean and safe while creating a comfortable environment for swimmers and bathers. There are several different chemicals needed to properly maintain the water chemistry balance. Adding them to the pool in the proper order and after waiting for the proper amount of time is essential.  How long do pool chemicals take to work? In this article, we’ll go through the steps necessary to get your water chemistry in balance.

Swimming Pool Turnover Rates

The amount of time that you should allow to elapse before adding a regimen of chemicals depends on the volume of your pool and the power of your water pump. What you’re looking to determine is the turnover rate which is the amount of time it takes for the entire contents of the pool to be cycled through the water pump and filtration system. Ideally, your swimming pool will have a turnover rate of six hours. At the very maximum, you’d want a turnover rate of no more than 12 hours. But with an optimally working system, six hours or less should be the norm.

Total Alkalinity

Total alkalinity is where you should begin when performing your water tests and adding chemicals to the pool. The reason for this is that if the total alkalinity isn’t properly balanced the tests that come afterward, especially for pH, will be skewed and difficult, if not impossible, to regulate. By getting your total alkalinity within the correct range, you’ll have a much easier time with the rest of the chemical regimen. When making adjustments to total alkalinity, you should wait for the turnover cycle to complete – ideally six hours or less in a properly functioning pool. This ensures the total alkalinity levels are stable allowing further tests to be accurate Moving onto the pH adjustments too quickly can result in erratic fluctuations that are hard to control. Once your total alkalinity has stabilized between 80 and 120 ppm, you’ll be able to move on.


Fortunately, pH adjustments don’t require as much waiting time as total alkalinity adjustments. Once the total alkalinity is stable, you’ll have a much easier time with pH. After adding pH increaser or decreaser you’ll want to wait about two to four hours, although some chemical manufacturers suggest a full turnover cycle, before retesting. The smaller the increments you need to adjust for pH, the less time you’ll need to wait for the results to become stable. Similar to how total alkalinity affects your ability to adjust pH, getting the correct pH levels will affect the ability of chlorine to do its job.


When shocking your pool with chlorine, you need to get it to the breakpoint level to ensure effectiveness. This is usually 10 times the level at which you would normally maintain your pool water. For example, if your chlorine level is typically 2ppm, to properly shock the pool you would need to bring it up to 20ppm. Because chlorine becomes unstable in sunlight, you want to shock your pool in the evening and allow it to work overnight. First of all, measure the chlorine levels before shocking the pool and then test again after about 30 minutes. You can perform your final chlorine test in the morning. 

Cyanuric Acid

Cyanuric acid is a stabilizer that allows chlorine to withstand sunlight better. Powdered stabilizers can take quite some time to properly dissolve and circulate. When adding cyanuric acid, you should add half the estimated amount, allow for a single turnover cycle, and test again before adding the rest of the dose. Test again a week later to ensure the desired target has been maintained.

To learn more about keeping your pool sanitary and clean, download a Backyard Escapes Guide.

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