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May 24, 2021

How Does Rain Affect My Pool?


If you are a new pool owner, you may wonder what effect, if any, rainwater will have on your pool. The truth is that rain can affect both the chemistry of the water and the ability of the skimmer to function optimally. Let’s look at what can happen to your pool during rainfall and what you can do about it.

Water Levels Increase

When it rains, the water level in your pool rises. If the water reaches a certain level, then the skimmer will stop working, which means that the water in the pool will not continue circulating, and the surface of the pool will no longer be skimmed properly. As a result, leaves and bugs accumulate on the surface before settling to the bottom. 

Solution: Pump the water out or backwash the pool to get the water down to the level recommended by your skimmer’s manufacturer.

pH Level Decline

One of the most important measurements of your pool’s health is its pH level. You can easily determine the pH level and more with a testing kit available from your choice of swimming pool companies in Chester County. The amount of change in your pool’s pH due to rainfall is normally negligible unless there is a heavy period of rain occurring over several days. 

Solution: You may need to add a balancing chemical to raise the pH in this case.

Alkalinity and Calcium Changes

Rain decreases the total alkalinity in your pool by up to 10 ppm per day, creating a corrosive environment that can damage the pool and its components. To correct it, adjust the pH, calcium hardness, and total alkalinity. Adding hundreds of gallons of rainwater to your pool can also decrease its overall calcium hardness. 

Solution: The fix is to add calcium hardness to the pool to bring it to the desired level.

Chlorine Dilution and Algae Blooms

Chlorine in your pool is diluted by rainwater. Prepare for inbound storms by raising your pool’s chlorine levels if needed. Add chlorine to bring it up to the appropriate level after the storm is over. Moreover, rainwater gives algae a great place to get a foothold. Dose your pool weekly with algaecide to help stave off algae.

Ready for your own backyard paradise? Reach out to Carlton Pools for custom swimming pools in Chester County.