How to Lower a High Chlorine Level in Your Pool Quickly

Chlorine is one of the most effective disinfectants for your pool, but it often happens that beginners use too much chlorine for pool maintenance. As a result, the chlorine level in the pool gets too high, and all kinds of symptoms occur. What to do and how to lower the chlorine level in your pool?

If the chlorine level in the pool water is too high, it usually breaks down on its own if the pool is exposed to the sun’s UV rays and the pool pump is running. In addition, a chlorine neutralizer or hydrogen peroxide can be used if there is too much chlorine in a pool.

I will explain how to recognize the first symptoms of a high chlorine level in your pool and how to lower the chlorine level. In the article, you will also find helpful tips from experts to avoid an overdose of chlorine in your pool water.

Symptoms of too much chlorine in your pool

A water test shows you if there is too much chlorine in your pool. But you have to know how high the chlorine level in your pool should be.

The ideal chlorine level in your pool should be between 0.3 and 1.5 ppm – In some regions of Spain and the US, the chlorine level can be increased to 2 ppm due to the climatic conditions.

If the measured total chlorine level is above the optimum, we talk of an over-chlorination in your pool.

Measuring the chlorine level with test strips or an electronic water tester is one way of finding out whether there is too much chlorine in your pool water.

But the over-chlorination of your swimming pool can also be guessed from the following symptoms:

  • Red and burning eyes when swimming in the pool.
  • Rash in the form of chlorine acne (chlorine allergy).
  • After the pool shock, your pool is milky and cloudy.
  • The typical smell of pool water indicates too many chloramines.

So far, these are the most common signs that the chlorine concentration in your pool is above the optimum.

Another question is why the chlorine level in your pool is too high in the first place.

Why is the chlorine level in the pool water too high?

  • Incorrect measurement methods: Bad test strips are used to determine your pool’s free and bound chlorine level, which often gives a wrong result. This leads to an overdose of chlorine.
  • Incorrect dosage: You follow the wrong advice regarding chlorine dosage in your pool and ignore the manufacturer’s instructions.
  • Unsuitable equipment: Perhaps your metering floater or an incorrectly set chlorine metering sluice is causing too much chlorine to end up in the pool.
  • Too much chlorine stabilizer: You use too much cyanuric acid (chlorine stabilizer) and forget that the acid in your water is not broken down.
  • Chlorine consumption is low: If your swimming pool stands in the shade, the chlorine is not neutralized by the sun’s UV rays, and the general chlorine consumption is low.

Here is a helpful table for the correct chlorine dosage with the recommended levels ​​according to DIN 19643 for chlorine in swimming pools.

Free Chlorine Bound Chlorine
Indoor Pool 0,4 ppm 0,2 ppm
outdoor Pool 0,8 ppm 0,2 ppm

How to reduce the pool chlorine level in your pool

If your chlorine concentration in your pool water is too high, you can read here how to reduce the chlorine level.

1. Do not add any more chlorine to your swimming pool

If you find out that your pool has too much chlorine, then you need to get all of the chlorine out of your pool water.

To do this, switch off the salt electrolysis device in your saltwater pool and remove all chlorine tablets from the pool floater and skimmer.

Tip: Read my guide on how to use chlorine tablets in a floater and reduce the risk of a high chlorine level in your pool water.

Then you wait until the chlorine has broken down in the water by itself – the chlorine level should not drop below 0.3 ppm.

But, this will not work if you had used a chlorine stabilizer in your saltwater pool. In this case, jump forward to the third step.

2. Lower the chlorine level with the help of the sun

Direct sunlight ensures that the chlorine level in your pool drops.

The only question is: How quickly does the chlorine break down with this method?

Depending on the intensity of the UV radiation and the volume of your pool, this can take several hours.

If your pool is in the shade, it logically takes longer.

Remember that if there is too much chlorine stabilizer in your pool, the chlorine level will not drop on its own.

3. Neutralize the chlorine with a chlorine neutralizer

The quickest way to reduce excessive chlorine levels in your pool is to use a chlorine neutralizer.

When using it, more mindfulness and a precise approach are required.

That’s why I explain here with an example how to use the chlorine neutralizer to lower the chlorine in your pool.

Info: In a pool with 100 m³, 100 g of the chlorine neutralizer are sufficient to reduce the chlorine level to 0.5 ppm.

  • Example: The chlorine concentration in your pool is 4 ppm, and your swimming pool has almost 50 m³ of water.
  • Question: How much chlorine neutralizer is needed to reduce the chlorine level to 1 ppm?

Remember: 50 m³ corresponds to 0.5% of 100 m³.

Calculation: 0.5 * 100 g = 50 g each 0.5 ppm.

We want to lower the chlorine level from 4 ppm to 1 ppm. That means a reduction of the chlorine by 3 ppm.

This results in the following final invoice:

6 x 50 g = 300 g are required by the chlorine neutralizer to lower the chlorine content from 4 ppm to 1 ppm in your pool.

Caution: The calculation example relates to 50 m³ of water content and not to the size of your pool. In theory, your pool can be 75 m³ and only hold 50 m³ of water.

4. Use hydrogen peroxide against chlorine

Hydrogen peroxide can be used to lower the chlorine level in swimming pools.

Just make sure that the pH level is 7.0 or higher because this is where the hydrogen peroxide works best.

When using it, you should strictly follow the information provided by the manufacturer.

In addition, the pH level in your pool will drop after use – so you must then measure the pH level and, if necessary, optimize it to 7.2 to 7.6.

Read my instructions on how to raise the pH level in a pool. Click on the link to read the post.

5. Water exchange if there is too much chlorine in your pool

If you don’t have a chlorine reducer or hydrogen peroxide at hand, you can quickly drain a part of your pool water and fill it with fresh water.

To do this, you can simply set your sand filter system to emptying, or you use a submersible pump.

This method will lower a high chlorine level in your pool and all other agents in your pool water.

You then have to measure the water levels ​​and, if necessary, correct the cyanuric acid, the pH level, the total alkalinity and the calcium hardness of your pool water.

How to completely remove the chlorine from your swimming pool?

Do you want to maintain your pool without chlorine in the future and switch to an alternative disinfectant product?

Now you are wondering how to get out the chlorine of the water?

You can start using the new disinfectant product and simply wait until the chlorine has broken down by itself.

That works so far when switching to Bromine or active oxygen.

However, the situation is different if biguanides are used in the future because chlorine must be removed entirely beforehand.

How to remove the chlorine and all other halogens disinfectants from your pool:

  1. First, scrub the floor and walls thoroughly with a pool brush to remove any chlorine buildup.
  2. Then the swimming pool is vacuumed through the sand filter system – in the emptying position – with a pool vacuum.
  3. Backwash the sand filter system, and don’t forget to rinse afterward.
  4. Now use the chlorine neutralizer as described above.
  5. Finally, the filter system has to run for 24 hours.

Do a final chlorine test. Is chlorine still available in your pool?

If so, repeat the steps.

Do you want to run your pool without chlorine?

Great!

In my blog post, you will find helpful instructions on how to clean your pool without chlorine – just follow the link.

Can you swim in your pool with a high chlorine level?

If a chlorine level is measured above the optimum, you should not swim in your pool under no circumstances.

Chlorine is a toxic chemical and can make you sick.

Frequent consequences are breathing difficulties, irritated eyes, allergic reactions to the skin, and in the worst case, cancer.

That is why you usually wait 24 to 36 hours after a pool shock – with the pool pump running – until the chlorine level has dropped below 1.5 ppm.

You have to lower the chlorine level to swim safely in your swimming pool again.

Tip: You can read in my blog how to properly do a pool shock. Follow the link to read the post.

Consequences of a too high chlorine level in the pool

Over-chlorination of pool water has more consequences than just red and stinging eyes.

But is it really that bad if there is too much chlorine in your pool water?

The short answer: Yes, too much chlorine in your pool harms all bathers and your pool equipment.

  • Chloracne: If there is too much chlorine in the swimming pool, people may have an allergic reaction, and chlorine acne develops.
  • Irritation of the skin and respiratory tract: When used correctly, chlorine is a good disinfectant, but too much will irritate the skin and the respiratory tract. In the worst case, asthma results from too much chlorine in the pool water.
  • By-products from too much chlorine: When chlorine reacts with sweat, urine, or other organic substances, chloramines and trihalomethanes are formed. These cause the typical chlorine smell and can even lead to cancer.
  • Green hair, nails, and clothing: A common problem from chlorine overdose is green hair, nails, and clothing.
  • Bleach stains in the pool: Bleach stains in the swimming pool cannot be removed and are another consequence of the incorrect use of chlorine tablets.
  • Damage to the pool equipment: If there are too many chlorine tablets in the skimmer or the basket of the pool pump, then a chlorine liquid is created, which has a corrosive effect on the entire pool equipment.

Another consequence, if too much of the combined chlorine – chlorine that has already been used – is present in the pool water, the disinfecting effect is reduced.

As a result, algae multiply, and the pool water turns green.

If you already have green pool water, then stop here briefly. Read through my helpful guide against green pool water.

Do you have any further questions about the chlorine level in your pool?

Contact me at @contactswimfool on Twitter, Facebook, Pinterest, and other social media – I’ll help you personally.

With this in mind, I hope you enjoy swimming!

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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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