Your pool’s pH is a measurement of the hydrogen ion concentration in the water. The pH is important because it not only affects pool maintenance but also the comfort of swimmers. pH stands for “power of hydrogen”. Since water is easily ionized and conducts electricity, it will always contain some hydrogen ions. The pH scale is set up so that the higher the pH number measured in the water, the more alkaline it is and the smaller the pH number, the more acidic it is. As part of pool maintenance, it’s important to learn how to lower the pH in a pool.

How to Lower the pH in a Pool

In this post, we’ll discuss why it’s important to keep your pool’s pH balanced and how to lower the PH of your pool. Controlling the pH is crucial to ensure your pool is comfortable for swimming and also to prolong the life of materials that make up the pool.

How to Lower the pH in a Pool
How to Lower the pH in a Pool

Why Does Your pH Need to be Balanced?

Teardrops from the human eye have a pH of 7.5, as such, having a pH close to that number will make swimming in your pool more comfortable. Sometimes, swimmers complain that their eyes are hurting because the chlorine levels are too high. However, in most cases, this is caused by an unbalanced pH rather than a high chlorine level.

Common Problems Caused by a Low pH

  • Skin and eye irritation
  • Wrinkles in vinyl layers
  • Chlorine loss
  • Staining
  • Metal corrosion
  • Etching of the pool surface
  • Algae can begin to form in the pool

Common Problems Caused by a High pH

  • Eye and skin irritation
  • Chlorine inefficiency
  • Cloudy water
  • Scaling (which can result in reduced circulation, clogged heater elements and clogged filters)

Controlling Your Pool’s pH

Industry experts say to raise the pH: sodium carbonate (soda ash) is normally used. Baking soda (sodium bicarbonate) can be used to raise pH if the pool water has low alkalinity but it’s more commonly used to raise alkalinity.

To lower pH: The most commonly used liquid to lower pH is muriatic acid (hydrochloric acid).

How to Lower the pH in a Pool
How to Lower the pH in a Pool

Lowering the pH In A Pool

The amount of acid you’re supposed to add to your pool to lower the pH depends on the size of the pool and the pool’s pH reading. If you’re using a test strip, determining exactly how high your pH level is can be tough, all you know is that it’s just high. Consider using a better test kit, such as a DPD drop test kit that will give you a better idea of the true pH reading.

If you have a pH reading of 7.8 or higher, you need to add about a quart (1/4 gallon) of muriatic acid to an average-sized in-ground pool (15,000 gallons). You should then retest the water after it has circulated for an hour. If you have an above-ground or smaller pool, start with a cup of acid and re-test and add more if needed. 

Bottom Line

Now that’s how to lower the pH in a pool. When adding acid, be sure to pour it in the deepest part of the pool while the pump is running so the water can circulate. Wait at least an hour before using the pool; but if you added a lot of acid, give the pool for about 24 hours for the water to circulate then retest the pool before using it. Remember to also clean your pool and maintain it regularly.

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