What Causes Low pH in Swimming Pools?

In order to have a sparkling, safe swimming pool, its chemistry must be perfect at all times. One of the most important elements to achieving this is having the right pH balance. The pH, or “potential of hydrogen,” measures the acidity or alkalinity of your pool, and it should be maintained at levels between 7.2 and 7.8.

You may already know what causes high pH and alkalinity in pool water and how to combat it, but in this article, we will discuss the main causes of low pH and how to raise the pH in a swimming pool.

What Is pH in Swimming Pool Water?

The pH level is the measure of how acidic or alkaline the water is. On a scale ranging from zero (highly acidic) to fourteen (highly alkaline), the ideal pH of pool water is between 7.2 and 7.8. 

This is important for a number of reasons. Chlorine, the most commonly used sanitizer in swimming pools, is only effective in killing germs and bacteria when the pH level is within the recommended range. Also, a pH level outside this range can lead to discomfort, irritation, and health hazards for users.

Potential Causes of Low pH


If it has been raining heavily and your pool is uncovered, the water may experience a drop in pH levels. This occurs because rainwater is slightly acidic and can alter the pool’s chemical balance.

Low Total Alkalinity

Total alkalinity refers to the amount of alkaline substances in pool water, and when this is low, pH levels will drop. Pool owners can use alkaline products to increase total alkalinity levels, which should range between eighty and 120 parts per million (PPM).

Chemical Imbalances

If pool chemistry is out of sync, this might result in pH levels being too low. If such issues are addressed incorrectly and the wrong quantities of chemicals are used to solve the problem, the situation can worsen.

Acidic Water

Be sure to check the pH of the water source used to refill your pool, as an acidic water source will cause an immediate decrease in pH levels.

Ways to Increase pH in a Swimming Pool

If you know your swimming pool has a low pH, there are several steps you can take to restore the proper balance.

Add a pH Increaser

Sodium carbonate, also known as ‘soda ash,’ is the most effective way to increase pH levels. It is best to sprinkle it around the perimeter of the pool, let it dissolve, and run the pool pump for several hours to ensure the product is adequately distributed throughout the pool water.

Add Baking Soda

Baking soda, or sodium bicarbonate, is a naturally alkaline product. When added to your pool, it will raise pH and alkaline levels. This is a cost-effective solution, although it is more time consuming than using stronger pH increasers. 

Check Sanitizer Level

Properly sanitizing pool water is an important step in maintaining correct pH levels. Most sanitizers release small amounts of calcium hydroxide and calcium carbonate, which increase pH and total alkalinity. Regularly check sanitizers and readjust them when necessary.

Concluding Thoughts

Your pH level maintenance in swimming pools is essential to ensuring swimmer safety. What happens when pool pH is too low? Decreased levels can have adverse effects for swimmers in the form of discomfort and health hazards. Make sure you regularly check pH levels and follow the advice in this article to rectify any drops in these levels.

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