How to Lower Alkalinity in a Pool

By Shiloh McGinley

January 30, 2024

How to Lower Alkalinity in a Pool

How to Lower Alkalinity in a Pool

More than just picking up debris and scrubbing the pool’s surface, there’s more that goes into ensuring your pool’s water is safe to swim in.

From adding chlorine to ensuring proper PH and alkalinity levels, there’s a small list of boxes your pool’s water needs to check before it’s safe for you to dive in.

Though it might seem a lot of hassle for a new pool owner to manage, the solutions to these requirements are actually quite simple. Anyone can manage a pool’s maintenance as long as they have the right information and tools. 

In this article, we’ll be discussing pool alkalinity levels, what it is, what are its effects, and what to do if you find the levels are too high, of course the reason you're here; How to Lower Alkalinity in a Pool.

But first, the basics and WHY you should care.

Cloudy Swimming Pool Water

What is pool water alkalinity?

In simple terms, Alkalinity is the capacity of water to resist acidification. This means that having a pool with some alkalinity is actually a good thing for several reasons.

The main and most important purpose of alkalinity is that, in the swimming pool, it acts as a sort of buffer to stabilize pH levels, which is important to prevent scaling and other pool problems. 

With that in mind, know that as a pool owner, you won’t be trying to eliminate alkalinity from your pool completely.

You simply want it at levels where it can buffer against PH without causing damage to your skin or the pool.


There are several causes of alkalinity in the water. Knowing these causes can help you solve them and, hopefully, have to worry about your pool’s alkalinity levels less often. 

Too much baking soda

The first, and maybe most common, cause of high alkalinity is due to the addition of too much sodium bicarbonate (baking soda).

This usually happens when a pool owner finds that the alkalinity levels are too low and tries to correct it, leading to overkill.

Be wary of how much sodium bicarbonate (baking soda) you use and, to keep this from happening too often, use smaller increments of the chemical when adjusting alkalinity levels.

Test the water every 24 hours, adding only as needed until it reaches its ideal conditions.

We recommend an ideal alkalinity level of 80 ppm to 150 ppm, this is known as total alkalinity and helps keep the pH level stable.

The water’s source

The second cause of high alkalinity can be found in the source of the water used for the pool itself.

Since water companies are required to disclose their water testing results to their consumers, a simple call to the water company can inform you of the alkalinity levels of the water you use for the pool.

It might be likely that the levels were already ideal or maybe even high before you added the sodium bicarbonate. 

Pool shock

Another possible cause for high alkalinity is pool shock. While this is performed to quickly rid the pool of pollutants, chlorine-based pool shock is highly alkaline and can raise the water’s total alkalinity level in the process.


Lastly, swimmers themselves add alkaline to the pool. When a person goes for a swim, he or she brings pollutants clinging to the skin to the water of the pool.

This could be anything from sweat, natural body oil, sunscreen or lotion, or dirt and debris. This is why many public and private pools require visitors to bathe first before going for a swim.


When the PH and alkalinity levels of your pool are too high, it can lead to some costly problems.

  • Firstly, a pool with too high of an alkalinity level can is prone to scaling. This scaling can be seen on your pool’s surface as well as the plumbing and other equipment. Scaling happens due to the influx of calcium in high alkalinity water. The water as a result will appear cloudy. 
  • Secondly, high alkalinity can also make it very difficult to adjust the PH levels of your pool.

Both high pH and high alkalinity can cause some serious damage to the pool, the equipment attached to the pool, and the swimmer. It can also inhibit the effectiveness of chlorine, and prevent your pool from being properly sanitized. 

On the other hand, low alkalinity levels are not ideal either.

With low alkalinity, your pool pH can fluctuate at the slightest addition of an acid or base.

When the pH drops, the water can damage the pool’s walls, metals, and the skin of those swimming in it.

When all is said and done, your pool needs an equilibrium of both pH and alkaline at the right levels to be a safe place to swim.

This means regularly testing the water for this balance is something you should make a habit of.

Worry not though, there are some inexpensive and practical solutions to deal with high alkalinity that we talk about below.

How to take an accurate reading of the alkalinity of your pool?

Though testing for alkalinity is important, it’s luckily not as volatile as free chlorine or pH levels and does not require as frequent testing.

This makes alkalinity very similar to even correlated to cyanuric acid.

Overall, we would recommend that you test alkalinity levels, along with pH, at least once a week to be sure.


There are two very similar ways you can test your pools alkalinity level:

Swimming Pool Chemical Testing

Let's examine both. 

1) Test Strips

Relatively inexpensive and easy to use, test strips are strips you submerge in your pool for a few seconds.

Once nice and wet, you level them on one side and all the reagent chemicals on the strip to react with the water.

They will start to turn a specific color which you will then compare to a chart on the test strip’s packet. Use your best judgment to see if the color is within the ideal range.

2) Pool Testing Kits

Pool testing kits work generally the same as test strips but instead require you to take small water samples.

The samples would be contained in a test tube where you would then apply several drops of reagent.

Like the test strips, the reagent fully reacts with the water and produces a specific color. You compare the color of the test water with a color scale provided in the test kit.

Although the pool testing kit is more accurate than testing strips, any of the two will work just fine to inform you about the chemical levels of your pool.

How to Lower Alkalinity in a Pool, 2 Proven Methods

Once you’ve tested the pools water and found the alkalinity levels too high, there are 2 methods you can use to lower it:

Method #1: Muriatic Acid

Also known as hydrochloric acid, this is the most common way pool owners use to treat high alkalinity.

And with a pH level of only 1 to 2, it’s also the solution that’s less likely to affect any other chemical levels of the pool. This solution is quite affordable and strong enough to kill mold, remove rust, and rid the pool of calcium deposits.

On the downside, muriatic acid is very dangerous and can definitely cause harm with any contact with the skin. Protective google and long sleeves will be needed. 

Before pouring it into the water, be sure to turn off the pool pumps and filter first.

Muriatic acid requires stagnant pool water to lower the total alkalinity by the widest margin possible.

It usually requires about 25.6 ounces of full-strength muriatic acid to lower a 10,000-gallon pool by 10 ppm.

Read the instructions on the bottle for more accurate dosage. 

  • To make things safe for yourself, you can dilute the acid with water. 
  • Just add 1 part acid to 10 parts water. Use a plastic bucket and wooden stir stick.
  • Pour the solution into the deepest part of the pool and wait an hour or two before turning on the pumps again.
  • After a while, you can test the water again to see if it had an effect.

Method #2: Dry Acid

Another possible solution you can use is sodium bisulfate or dry acid. Though this is safer than muriatic acid, it’s also more expensive.

Read the instructions on the pack or bottle to know how much of the substance to use for your pool.

  • In a plastic bucket, add 3 quarters of water and then the measured amount of dry acid. 
  • Stir with a wooden stick until completely dissolved. Note that any undissolved granules of acid might sink to the bottom of the pool and damage the surface.
  • Pour the solution along the edge of the pool starting with the deepest end.
  • Wait a while then retest for pH and alkalinity levels.
  • Repeat the process if necessary.

Bottom Line…

And that was our article on How to Lower Alkalinity in a Pool! 

With some regular testing and inexpensive solutions, you can easily deal with high pool alkalinity and get your pool ready for some splashing fun in little to no time at all!

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Shiloh McGinley

About the author

Shiloh McGinley has been in and around swimming pools her whole life. She's seen a lot of products come and go, and she wants to share with you the best products that really work!

Shiloh is passionate about helping people stay safe in the water, and she loves educating others on how to choose the right pool products.

When she's not working, Shiloh enjoys spending time with her family and friends, and swimming - of course!

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