How to Lower Alkalinity in Your Pool: A Step-By-Step Guide

How to Lower Alkalinity in Your Pool: A Step-By-Step Guide

 Maintaining proper alkalinity of water is essential to maintaining a swimming pool. Sometimes the alkalinity of a pool rises beyond critical levels, which can cause serious, irreversible, and expensive issues. Let’s dive deeper into these aspects and learn how to lower alkalinity in a pool.

What Is Alkalinity in Pools?

In simple terms, Total Alkalinity (TA) in a swimming pool is the ability of the pool water to resist change in the pH value. The level of alkalinity of your pool will help maintain optimal pH levels, which are imperative in ensuring the safety of the swimmers and your pool equipment.

A good pH level for a pool lies between 7.2 and 7.8 on a scale of 1 to 14. Increased pH levels (alkaline) can put swimmers at risk of developing skin issues like rashes. In contrast, too low pH levels (acidic) can cause a stinging sensation in the eyes. You must also learn that alkalinity and pH in pools are closely related but somewhat different concepts.

Causes and Results of High Pool Alkalinity?

The causes of high pool alkalinity can be natural or artificial, but for the most part, it is almost always a result of some chemical imbalance in pool water. Alkalinity rises with the increased concentration of carbonates, bicarbonates, and sometimes hydroxides in the water.

The first and most common reason for high pool alkalinity is when you shock your pool, which may involve methods like adding non-chlorine shocks (for pools with saltwater) or using chlorine tablets.

Another big reason could be that the pool owner is using chemicals like soda Ash or Borax to raise the pH levels of your pool water to prevent chlorine loss after a shock. Using high alkalinity water (from a spring, etc.) to fill your pool can also contribute to the raised levels.

Consider using an excellent algaecide to reduce algae in your pool. Additionally, the buildup of too much algae can raise alkalinity. Using a faulty test kit can also cause false alkalinity level readings.

The ideal alkalinity levels in a pool vary between 80-150 ppm (parts per million), with 120 ppm being optimal. As we mentioned earlier, levels below this range will turn the water acidic, and levels above will turn it too alkaline.

Here are some consequences if you fail to lower the total alkalinity in such a pool:

  • High pH causes cloudy pool water making it hazardous to the human body and pool equipment.
  • Chlorine in your pool becomes less effective at sanitizing the water, which may cause an algae bloom.
  • Damage to skin/eyes and also to the swimming gear
  • Calcium buildup which leads to scaling on the pool walls, and the filtration system

Best Methods to Lower Alkalinity of Your Pool

The best and fastest method to lower the alkalinity of your pool is to use chemicals that lower the pH levels. Unfortunately, no natural or gradual process that helps lower pool alkalinity effectively and without causing other issues.

The most used (and effective) chemicals for treating high alkalinity levels in a pool are Muriatic Acid and Sodium Bisulfate. While there are other alternatives like carbonic acid, sulfuric acid, and hydrochloric acid, these two are the most common.

Before you choose any of these solutions to adjust the alkalinity of your pool, make sure to use a reliable test kit to get the best results.

How to Safely Add Muriatic Acid to Your Pool

Muriatic acid is a multi-purpose cleaner for your swimming pool and is similar to hydrochloric acid in composition. Apart from lowering the alkalinity, it can also clean pool surfaces, filters, and filter cartridges. Here’s the step-by-step method to use it: 

  1. Make sure the pool pump is running when you begin. 
  2. Wear protective equipment (glasses, gloves, etc.) before handling the acid because it is slightly corrosive on the skin.
  3. Prepare the appropriate amount of chemical based on the alkalinity level and pool volume by diluting it with water (if needed). You can find this information mentioned on the packaging label, or you may use a pool calculator
  4. Pour this liquid into the water at different areas of the pool. Allow it to settle down for an hour. 
  5. Keep the pool pump running for 5-6 hours, and test the alkalinity levels after 24 hours.
  6. Repeat the above process if the alkalinity level has yet to come down as expected. 

How to Use Sodium Bisulfate to Lower Alkalinity in the Swimming Pool

Sodium Bisulfate, also known as dry acid, is an effective pH reducer and works the same as muriatic acid. It works slower than muriatic acid, costs a bit more, and requires protection against moisture, but it is also a safer option. 

  1. This pH decreaser comes packaged in powder form, and the first step is to calculate the amount needed for your pool.
  2. Take water in a bucket/container and add the powder while stirring the mix properly.
  3. Make sure no granules are undissolved, as they may damage the pool’s surface.
  4. Pour this mixture into the water moving around the perimeter of the pool. 
  5. Let it sit for an hour before powering on the pump
  6. After 24 hours of adding the dry acid, check the alkalinity levels and repeat the process if needed. 

    Lower Alkalinity without Lowering pH in a Pool

    Using muriatic acid or sodium bisulfate comes with consequences. Both of these chemicals lower the alkalinity of pool water and reduce the pH level. The pH could be acceptable, but the alkalinity could be too high. Keep in mind the importance of lower alkalinity but not pH in pool water. 

    Technically speaking, lowering alkalinity will lower the pH levels, so the solution lies in adding an extra process. After you treat your pool with muriatic acid or dry acid, use the aeration process to introduce pool water to more air. 


    The best way to prevent the total alkalinity of your pool from rising is to keep the pH levels in check. However, if it has already gone up, the best method is to use muriatic acid or sodium bisulfate to bring these values down to normal levels.

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