How to Lower Alkalinity in Pools (2 Methods)

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How to Lower Alkalinity in Pools

Pool water requires proper balance to remain safe for the swimmers. Therefore, when the alkalinity level is too high, there will be problems. Common issues that result from high alkalinity include irritation to skin irritations, burning eyes and premature degradation of swimsuits.

Additionally, high alkalinity can reduce the effectiveness of chlorine in sanitizing the water as it affects the pool chemistry. Also, you are more likely to end up with cloudy water, and the pH levels will also rise.

It is crucial to know how to lower alkalinity levels, but you should always start by understanding the optimal level to target and how to measure alkalinity.

What's the Optimal Level of Alkalinity in Pool 

Alkalinity will exist as a bicarbonate material in pool water, and hence the total alkalinity measures the amount of this substance in parts per million. Also, the total alkalinity will measure the buffering ability of the water to prevent changes in pH levels.

An ideal pool alkalinity level is between 80 and 120 ppm. Anything below 80 ppm means that you need to raise the level by adding baking soda or other suitable alkalines. If it is above 120 ppm, you need to lower it using muriatic acid or dry acid.

How to Test Alkalinity in Pool Water

Total alkalinity in pool water is not as volatile as pH or free chlorine level. However, it is still essential to test it at least once a week.

Test strips provide the easiest and most cost-effective way of testing the alkalinity levels. Although each type comes with specific directions for testing alkalinity, the process typically involves submerging the test strips in the pool water for a few seconds and allowing them to rest as the reagents react with the water.

The strips will change color. Comparing the color with the provided scale helps you determine the alkalinity level. It is essential to use high-quality test strips like JNW Direct Pool and Spa Test Strips for accurate and reliable results.

Besides test strips, you can also measure alkalinity levels using digital test kits such as the LaMotte 2056 ColorQ Pro 7.

2 Methods for Lowering Alkalinity in Pool 

Regardless of which method you use, you have to test the levels before you start and after you finish. Also, before you begin handling any of these pool chemicals, you should wear protective gear such as safety goggles and acid-resistant gloves.

Here are step by step directions for lowering alkalinity using the two most common methods: dry acid and muriatic acid.

Method 1: Using Dry Acid

Dry acid or sodium bisulfate comes in a granular form, and it will be safer to handle than muriatic acid. However, it also costs much more.

Step 1 – Test the Alkalinity Level

You need to test the alkalinity to determine the actual level before adding any chemical to the water. Here digital testers will give you the most accurate results, but test strips can also be helpful if you want an inexpensive option.

Also, remember to test the levels several times at least a few hours apart to ensure you get accurate results. Alkalinity levels often go down on their own, so testing several times will help you determine whether any intervention is necessary.

Step 2 – Determine How Much Dry Acid to Use

Next, you should determine how much dry acid to use. The actual alkalinity level in your pool water and the directions on the dry acid packaging should guide you here. You need to add just the right amount to get to the 80 and 120 ppm optimal level.

Step 3 – Mix Dry Acid with Water

Once you know how much dry acid to use, you need to dissolve the granules in water. Here you will need to fill a bucket of water to around three quarters and then pour in the dry acid.

Most manufacturers will provide specific dry acid to water ratios, and so you should stick with them if they are available.

Step 4 –  Pour Solution Around the Pool's Perimeter

After making sure all the granules dissolve in the water, you should add the mixture to the pool. Here, the best idea is always to pour the mixture around the pool's perimeter to ensure faster solution distribution.

Step 5 –  Retest Alkalinity and pH Level

You should give the dry acid a few hours to work, and then you can retest the alkalinity and pH levels to be sure it worked.

Method 2: Using Muriatic Acid

Muriatic acid is primarily hydrochloric acid, and it comes in liquid form. It is the most preferred method for lowering alkalinity, but the compound is highly volatile, so you need to take extra precautions.

Step 1 – Test Alkalinity Level

Like when using dry acid, the first step should be to test the alkalinity to be sure how far you will need to lower it and hence the amount of muriatic acid you need.

Step 2 – Turn Off the Pump and Water Features

Muriatic acid works best in still pool water, and so you need to turn off the pump and other water features before you add it to the pool.

Step 3 – Determine How Much You Need

Next, you should determine how much of this acid you need. Manufacturers provide clear direction on how much to use. Combining this information with your alkalinity measurements should help you figure out how much to use.

However, note that you need at least 50 fluid ounces of muriatic acid to lower alkalinity by 10 ppm in a 20,000-gallon pool.

Step 4 – Pour the Acid on the Deep End

Once you determine the amount of muriatic acid you need, pour it into the pool's deep end and give it at least 1 hour to mix with the water to lower the alkalinity.

Step 5 –  Retest Alkalinity

The last step is to turn on the pump and allow it to run for a few minutes before retesting the alkalinity to determine if the level is okay or you need to repeat the process.

Bottom Line

A high alkalinity level can cause all kinds of issues for your pool, from making the water uncomfortable for the swimmers to causing scaling and reducing the effectiveness of chlorine.

Regular alkalinity measurement helps ensure the level remains within the recommended levels. If it is too high, you can quickly bring it down using muriatic acid or dry acid.