How Sunlight Affects Chlorine

You know chlorine is necessary to keep your pool environment friendly, but did you know that chlorine can be affected by sunlight? It’s true. Those toasty warm sun beams are doing more than just keeping you warm. Let’s dive in. 

How Chlorine Works

Most of us have a basic understanding of how chlorine works. It sanitizes the water in your pool by eliminating bacteria and algae as it comes into contact with it. Once the chlorine comes into contact with the germs, it becomes what is known as combined chlorine. Combined chlorine is basically chlorine that’s been used, so it’s no longer disinfecting anything in your pool. It’s done its job. The chlorine that’s left is known as free chlorine. The free chlorine is what you want to make sure you have enough of in your pool when there is bacteria and algae present. It’s the chlorine that can still disinfect. It’s also the chlorine that can be affected by sunlight. 

How Sunlight Affects Chlorine

Chlorine can be broken down by sunlight. When the sun’s UV rays hit chlorine molecules, they disintegrate and chlorine gas is released into the air. Under the right conditions, like a particularly sunny day, this process can happen quite quickly. According to, the sun can cause chlorine to decrease by 90% in two hours. That’s quick. That’s also why it’s so important to maintain your chlorine levels. But balance is key. Too much chlorine can cause painful skin and eye irritation. 

Heat is another factor that can affect your chlorine levels. Since bacteria and algae both grow faster and proliferate well in higher temperatures, your chlorine is used up more quickly. That means there’s more bacteria to kill in the warm water, so there’s more combined chlorine (the chlorine that’s been used up) and less free chlorine (the chlorine that can still sanitize.)

Ways to Mitigate

But wait before you get stressed about chlorine levels. There are some fairly simple ways to mitigate the loss of chlorine through sun exposure. Before you build your pool, consider the best place for it. Is there a part of your property that is more shaded and less exposed to the sun? Building your pool in a cooler, less sunny spot can easily help prevent some of the loss of chlorine to sunlight. 

Next, you can always make sure to check and properly maintain your pool chemical levels. One way to ensure your chemical levels are always taken care of is to hire our professionals at A-Quality Pools for weekly pool maintenance. If you’ve ever wondered, “Is there pool maintenance near me?,” the answer is yes, and we’d love to help you out! Our professionals will make sure your pool chemical levels are balanced, so that your chlorine levels are optimal and protected from sunlight damage. That way, you can swim free and clear on those sunny summer days. 

Let us take care of all your pool worries, including maintaining proper chlorine levels during the sunniest, hottest months of the year. Give A-Quality Pools a call at 817-281-0781 or come check out the best selection of pool supplies that North Richland Hills has to offer.

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