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What Does Soda Do to Pool Water?

By Tony Guerra
In a swimming pool, the most common way to raise its pH level is by adding soda ash.

Maintaining a swimming pool properly involves a great deal of attention paid to its water chemistry, especially its disinfectant and pH levels. When it comes to pH in a swimming pool, keeping it within a recommended range is extremely important. One way of maintaining swimming pool pH is by raising or lowering its pH through the addition of various chemicals. For a pool owner, the common way of raising a pool's pH is by adding soda ash, or sodium carbonate.

Soda Ash

pH in a swimming pool's water is a measurement of how acidic or alkaline it is. Neutral pH is 7. Soda ash is alkaline and will help raise alkalinity in a swimming pool. Most often used in the making of glass, soda ash is also used in air purification and water softening. Soda ash also has a nearly identical sibling called sodium bicarbonate, or baking soda.


A swimming pool is most comfortable for a swimmer when it has a pH roughly between 7 and 8. Between 7.4 to 7.6 is actually a better pH range, though, and soda ash can quickly help bring a swimming pool to that slightly alkaline state. In addition, chlorine pool disinfectants work much better when pH in a swimming pool is well-balanced. If a pool's pH is below 7, chlorine will disappear and leave the pool with no disinfectant levels.

Raising pH

Adding soda ash to a swimming pool to raise pH involves spreading it around the pool. The amount of soda ash added to a pool depends on that pool's pH at the time of measurement. For a pool in which pH has dropped below 7, 1 to 2 lbs. of soda ash per 20,000 gallons of water will be needed, for example. If pool pH is only slightly below 7.4, about 12 ozs. of soda ash is all that's needed.


Pool pH and pool disinfectants complement and depend on each other to work well. If you add pool chlorine to maintain good disinfection, keep in mind that it will raise a pool's pH slightly. If your pool's pH goes above about 7.8, it will be necessary to lower it, which you can do using muriatic acid according to package instructions. Also, you can save a little money by substituting plain baking soda for soda ash using the same recommended amounts.


About the Author


Tony Guerra served more than 20 years in the U.S. Navy. He also spent seven years as an airline operations manager. Guerra is a former realtor, real-estate salesperson, associate broker and real-estate education instructor. He holds a master's degree in management and a bachelor's degree in interdisciplinary studies.