How to Raise Alkalinity in Your Pool in 7 Steps

Low alkalinity is terrible for the pool water quality and leads to cloudiness. But how can you increase the alkalinity in the pool?

The alkalinity in the pool is increased with an Alca-Plus (sodium carbonate). With 20 g of Alca-Plus, the alkalinity increases per 1 m3 water by 10 ppm. The maximum value of the alkalinity is 120 ppm. After increasing the acid capacity, the pH value in the pool may have to be lowered.

In these step-by-step instructions, I explain how you can increase the alkalinity in swimming pools and where you must pay attention.

1. Wear protective equipment

When raising the alkalinity in your pool, I always recommend wearing protective equipment such as rubber gloves, a respirator, and protective goggles.

If you don’t have safety glasses, at least wear sunglasses.

In general, you should protect your skin, eyes, and airways when using pool chemicals.

I also recommend that you always wear old clothes, as the acid can damage clothes.

2. Measure the alkalinity in the pool

Use photometric or titrimetric methods to measure acid capacity (alkalinity) and pH in the pool.

The use of test strips is not recommended. They are considered to be inaccurate.

I may recommend you an electronic water tester.

Stick to the following target value ​​for the alkalinity in the pool:

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

When optimizing the alkalinity in the pool, exact measuring methods are important, and you can do this best with the e-water tester.

Tip: In my blog article, I explain how to test the alkalinity in your pool if you need more information.

3. Determine the amount of Alca-Plus

To dose the right amount of Alca-Plus, you first calculate the pool volume.

Stick to the following formulas:

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

Follow the manufacturer’s instructions for dosing – see product packaging.

  • Alca-Plus (sodium carbonate): With 20 g, the alkalinity is increased by 10ppm for every 1 m3 of water.
  • TAC-Plus (sodium carbonate): With 20 g, the alkalinity is increased by 1.058 ppm for every 1 m3 of water.
  • pH stable (sodium carbonate): With 20 g, the alkalinity is increased by 8.9 ppm for every 1 m3 of water.

Don’t get confused by the names. For example, bicarbonate is nothing more than hydrogen carbonate.

Tip: I advise you to adhere to the manufacturer’s instructions and avoid overdosing strictly. Otherwise, the water will become cloudy.

4. Increase the alkalinity in the pool with the Alca-Plus

The Alca-Plus (pH-Plus) is available as a powder in pool shops.

You can add the agent directly to the pool, but the far better method is to liquefy the powder in a bucket of water beforehand.

To do this, pour a bucket of water and add the Alca-Plus to the water – please follow this order to avoid splashes.

The mixing ratio in the bucket of water should be 10:1.

Mix the mixture with a wooden or plastic stick, then pour the agent into the return flow of the pool pump.

This application leads to fewer splashes. Alternatively, you can pour the mixture into the pool from the pool edge.

Tip: Using the pH-Plus will increase the pH value. Do not worry about the pH in the pool at first. We will adjust the pH later.

5. Run the pump to raise the pool alkalinity

After using the Alca-Plus, I recommend letting the pool pump run for 1 1/2 hours.

As a result, the agent is better distributed in the pool water, and there are no stains in the pool.

Furthermore, the water is supplied with extra oxygen, which promotes the effect of the Alca-Plus in the bathroom.

6. Aerate the pool

As described in the article, extra oxygen and turbulence in the water can raise the pool alkalinity and pH level.

Usually, the pool pump will be enough, but pool accessories like a fountain can improve the effect.

If you already have a small fountain in your pool, let it run throughout the day.

7. One final water test

Let the remedy work in the pool for 24 hours and test the acidity of the water the following day.

Please do not use any water test strips. They are not sufficient to determine the alkalinity.

I recommend using an electronic water tester.

If the pool alkalinity is between 80 and 120 ppm, you can jump to the last step.

If the alkalinity in your pool water is still below 80 ppm, the dosage must be increased. You have to correct it a second time until the values ​​are correct.

8. Optimize the pH after raising the alkalinity

Once the pool alkalinity has been increased, the only thing left to do is slowly adjust the pH of the pool.

If you notice an increased pH value, I recommend adding a pH minus. Also, note the manufacturer’s instructions when using it.

If you are looking for a good pH minus, I recommend the remedy shown here.

When optimizing the pH value, it is always important to optimize the alkalinity beforehand.

Only afterward, you have to optimize the pH level to 7.2 – 7.6. You can read more about pool pH on my blog.

Why is the alkalinity dropping in the pool?

If the alkalinity in the pool is below 80 ppm, it must be increased as quickly as possible. Otherwise, the pH value will fluctuate significantly.

But why is the pool alkalinity too low? What are the causes?

If the measured value is below 80 ppm, there is too much acid in the water. The alkalinity usually decreases with the excessive use of cyanuric acid.

In this case, the pH value may be high, but the total alkalinity – as I said – is below 80 ppm.

And what can you do to increase the alkalinity in your pool?

A practical method is using an Alca-Plus agent, with which the necessary correction of the acid capacity in the pool can be made.

How to dose the agent exactly, I have described to you in detail above in the article.

Consequential damage caused by too low alkalinity in your pool

Is low alkalinity in the pool that bad?

The alkalinity (acid capacity) only influences the pH value. Could I wait to optimize the acid capacity in the pool?

It is true that acid capacity primarily affects pH, but the consequences of low alkalinity are far more significant.

  • If the alkalinity is low, the pH is also likely to be below 7.0. In this case, the water is acidic, and metal parts in the pool start to rust.
  • Acid water loosens the lime from the joints, and renovation work is required.
  • If the damaged joints are not repaired in time, dangerous black algae can nestle.
  • A low pH increases the oxidation of chlorine, which in turn leads to rapid consumption and additional costs for water treatment.

For these reasons, it is necessary to measure the alkalinity in the pool at least once a month and, if necessary, to increase it.

Tip: With an increasing number of bathers and frequent pool use, the alkalinity should be measured more than just once a month.

Questions and answers about the total alkalinity

In this chapter, I collect more questions from readers about what to do if the pool alkalinity is too low.

I hope to clear up any remaining questions. By doing this, I will improve your understanding of the alkalinity in the pool.

How does alkalinity affect water hardness?

The alkalinity interacts with the pH value. This means that if the alkalinity is too low, this is usually also the case with the pH value.

The same also applies vice versa.

Since the pH value influences the calcium hardness in the pool, these three parameters are therefore decisive for the water balance.

What is the lower limit for alkalinity?

From my experience, the pool’s limit of 80 ppm alkalinity should not be undercut – some blogs say the lower limit is 100 ppm in the US.

Test what works the best for yourself in your pool.

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

Can you increase the alkalinity with soda?

Some Alca-Plus products contain sodium hydrogen carbonate (NaHCO3), which is nothing other than soda (baking powder). Source.

As a result, the alkalinity can be increased with a home remedy – here soda.

But be careful: If the soda contains other organic ingredients, this can lead to over-saturation in the pool water and cloud the water.

The Problem with soda is, you need large amounts of soda to raise the alkalinity in your pool.

To increase the alkalinity by 50 ppm in a pool with 37 m³ of water, you need about 3.40 kg of soda. In a 50 m³ swimming pool, that would be around 5.10 kg.

I would generally advise against using home remedies for pool maintenance and cleaning.

Real professionals know how to use pool chemistry. Learn everything about it in my blog by following the link.

Did you understand everything?

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

With that in mind, have fun raising 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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