High Alkalinity in Pool (7 Steps to Lower Alkalinity in Your Pool)

Optimal alkalinity in the pool is crucial for crystal clear water. But what to do if the alkalinity in the pool is too high, and how can you lower the total alkalinity?

The total alkalinity in the pool should not exceed 120 ppm. If the alkalinity in the pool is too high, the alkalinity must first be reduced with a special acid between 80 and 120 ppm. Afterward, the pH value in the pool water is optimized to 7.2 to 7.6.

In this guide, I explain how to gradually lower the alkalinity (acid capacity) in the pool and how to maintain the parameter.

1. Wear protective equipment against acid splashes

An acid (especially for the pool) is required to lower the pool alkalinity. It is therefore important to wear protective equipment before use.

That would be rubber gloves and safety glasses.

The acid is aggressive and very irritating. Splashes damage the skin and mucous membranes.

If you don’t have safety glasses, at least protect your eyes from splashes with sunglasses.

Extra tip: It is best to put on old clothes, as the acid can damage the clothes.

2. Measure the total alkalinity in the pool

Before pouring any agent into the pool, you must test your pool water.

Test strips are available in pool shops that can measure the acid capacity in the pool, but these are not precise and therefore not recommended.

I recommend the photometric or the titrimetric test method because the alkalinity depends on the exact determination of the concentration in the pool water.

A level between 80 and 120 ppm is acceptable. Anything below or above the ideal pool alkalinity must be corrected.

Setpoints of the alkalinity in the pool:

0.8 to 1.2 mmol / l = 80 ppm to 120 ppm = 80 to 120 ppm = 4.48 to 6.72 ° dH

Don’t worry about the pH level now. We will correct it later.

Tip: With an exact value of the alkalinity, later you will not have any problems optimizing the pool’s pH value.

So invest in a sensible water tester right away – I recommend electronic devices.

3. Determine the amount of hydrochloric acid

The funds available in the US for the pool are marked with warnings and quantities.

Every product contains a different concentration, and it would be not responsible if I threw any numbers at your head.

First, calculate the pool volume:

  • Rectangular basin: length x width x average depth
  • Round pools: Radius² x 3.14 x depth (r² * π * h)
  • Free forms: Here, the water content must be roughly estimated.

When dosing the hydrochloric acid, strictly follow the manufacturer’s instructions – the pH minus is acid.

With the water test, you know how high the alkalinity in the pool water is.

The information on the packaging tells you how much of the agent you have to pour into the pool.

If you have problems, try an online calculator, but you can usually get by without it. Source.

Info: It doesn’t matter that the pH value drops by adding acid. We will correct the pH in a further step.

4. Lower the alkalinity in the pool

The agent to lower the alkalinity in the pool is mainly sold as a powder and is nothing more than a pH reducer.

You can sprinkle the pH reducer directly into the pool.

Still, I recommend dissolving the acid in a bucket of water beforehand and then pouring it into the pool in liquid form.

Here it is important that when liquefying pool chemicals, you always add the chemicals to the water and never the other way around.

First, fill a bucket with water and then carefully pour the pH reducer into the bucket – the mixing ratio should be 10:1.

Use a wooden or plastic stick to stir until the powder has liquefied.

Then you carefully pour the agent over the pool edge into the pool – even better in the return flow of the pool pump to avoid splashes.

Tip: It’s best to distribute the amount in different places so that the agent is well distributed in the pool water if you don’t have a pool pump.

5. Run the pool pump

A running pool pump enriches the pool water with extra oxygen. In addition, the water in the pool is swirled.

Both increase the alkalinity and the pH value. It is important to prevent this when lowering the alkalinity in your pool.

By switching off the pump, you prevent the pH value from being influenced too much in addition to the alkalinity – at least in theory.

But if the pump is switched off, there is a risk that the agent will not be adequately distributed in the pool and settle on the pool floor.

In this case, the acid can damage the pool.

Play it safe and let the pool pump run for 1 1/2 hours. In this way, the pool chemistry is better distributed, and the effect is improved.

My tip: If you let the pool pump run, you can pour the acid directly into the return flow of the nozzles – this minimizes splashes on clothing.

6. One final water test

Then let the pool rest for 24 hours and test the water values ​​for the total alkalinity in your pool the next day.

If the values ​​are in the ideal range between 80 and 120 ppm, you can jump to the last step.

If the alkalinity in the pool is still high, repeat the steps until the total alkalinity in your pool water is at 80 to 120 ppm.

7. Increase the pH value with a pH elevator

If we lower the alkalinity in the pool, the pH value will most likely also decrease – I am not aware of a pH-neutral agent at this point.

In the last step, you now have to measure the pH value and, if necessary, correct it upwards.

Unless the pH value deviates significantly from the optimum (7.2 to 7.6), the pool pump can be run for another day so that the water is circulated and supplied with extra air.

That should raise the pH.

Test the pH in the pool again the following day.

If the pH value is still too low, in this case, you can increase the parameter with a pH plus.


The total alkalinity should be back to normal according to the instructions.

In the following text, you can read about what increases the alkalinity and the consequential damage if the pool’s alkalinity is too high.

Why is the alkalinity increasing in the pool?

When filling the pool, it can happen that the delivered water already has high alkalinity.

Furthermore, the following causes lead to the total alkalinity in the pool increasing.

  • Bad bathing habits: No showering before entering the pool will cause the alkalinity in the swimming pool to rise.
  • Abuse as a toilet: Urine and other substances cause the pool’s alkalinity to rise.
  • High temperatures: But high temperatures also have an upward effect on the alkalinity. Source.
  • Water circulation: The swirling of the water leads to high alkalinity in your pool.

If the total alkalinity increases, so will the pH – you can read about the problems this creates further down in the article.

In theory, you can wait until the alkalinity in the pool water drops on its own. But that would take too long and is not recommended from a professional point of view.

As a pool owner, you have to lower excessively high alkalinity in the pool with acid.

I explained to you exactly how this works in the instructions above.

Now it is your turn.

Consequential damage due to high alkalinity in the pool

Is high alkalinity in the pool that bad?

The alkalinity only influences the pH value in your pool, and what can go wrong?

It is true that acid capacity primarily affects pH, but the consequences of incorrect alkalinity and pH values ​​are not negligible.

  • If the alkalinity is too high, the pH value fluctuates strongly, resulting in cloudy and green pool water.
  • A high pH value above 7.6 leads to cloudiness and limescale in the pool – fogged walls and filter sand, limescale in the pool.
  • The high alkalinity can cause the pool water to foam.

Therefore the alkalinity in the US should never be below 80 ppm or above 120 ppm in the pool.

Regular water tests with an electronic measuring device are essential to comply with the limit values in your pool.

A measurement of the total alkalinity is sufficient once or twice a month. It is only essential that the result is exact.

You can find more on this topic in the blog article – Testing the alkalinity in the pool. Just click on the link.

Questions and answers about a high pool alkalinity

This chapter collects the reader’s specific questions if the alkalinity score is too high.

I hope to clear up any unclearness about lowering the pool alkalinity that has not been dealt with in this way.

What to do if the alkalinity in your pool doesn’t drop?

If the pool alkalinity is dropping slowly or not, I recommend the steps I have shown on how to lower the total alkalinity.

With meticulous adherence to all steps and through the use of high-quality pH value reducers, the total alkalinity should return to normal quickly.

Please don’t wait for a high alkalinity concentration in the pool to drop by itself.

What is the maximum pool alkalinity?

In my experience, the pool’s limit of 120 ppm alkalinity should not be exceeded – some other blogs recommend 150 ppm.

As a pool owner, you can test what works best for your pool.

Tip: If your alkalinity in the pool is too low, read my step-by-step instructions on lowering the level under the link.

Despite the ideal total alkalinity, I have mustard algae in the pool

A reader contacted me and sent me the measured alkalinity and pH values.

Both parameters (alkalinity and pH value) were in the ideal range.

Despite the filter system and shock chlorination running, the problem with mustard algae could not be brought under control.

If so, the problem is likely with a high cyanuric acid level.

If the cyanuric acid exceeds 50 ppm, the chlorine loses its disinfecting effect, and algae can spread undisturbed in the swimming pool.

Can a home remedy be used to lower pool alkalinity?

If you want to lower the pool alkalinity, you can theoretically do it with a simple home remedy.

All it takes is an acid like vinegar or citric acid, but I wouldn’t recommend that.

The reason why you shouldn’t use home remedies for treating pool water is that you need large quantities and that precise dosing is usually not possible.

In addition, most home remedies contain additives that have no place in the swimming pool or whirlpool.

Therefore, only use certified pool care products and avoid advice recommending home remedies.

The later consequences and costs resulting from home remedies in pool maintenance exceed the utility factor.

If your question isn’t listed, contact me at @contactswimfool on Twitter, Facebook, Pinterest, and other social media – I’ll be happy to help.

With this in mind, I hope you enjoy lowering the alkalinity in the pool.

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Hi. I'm Max Berg. I've been in the pool industry since 2015 and have always felt drawn to water. I'm the author behind swimfool.com, where I share my years of experience in pool maintenance and give helpful tips on keeping a swimming pool or hot tub clean. My tips reduce the costs of water treatment and protect the environment.

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