Chlorine Remover For Pools

Chlorine Neutralizer / Remover For Pools - How Does It Work?

Chlorine is necessary in chlorine and salt pools for sanitation, but occasionally you may add too much by accident.

When researching remedies for this situation you will likely read about chlorine neutralizers, sometimes called chlorine removers, which are effective products for your situation. But how do chlorine neutralisers work?

Chlorine neutralizers or removers work by reacting with the chlorine that is present in your pool. After this reaction occurs, your chlorine levels are significantly lowered and your pool can once again be used safely.

In this article, we will discuss when you want to use a chlorine remover, the process behind how these products work, how to use chlorine neutralizers in your pool, and other ways you can lower your chlorine levels without a neutralizer. Let’s jump in!

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Why Use A Chlorine Remover?

Ideal levels of chlorine in your pool range from between 2-4 parts per million (ppm). If your pool has chlorine levels that lie above this range, they are too high and can have negative effects on your pool and its swimmers.

Reduce Swimmer Irritation

To start, high chlorine is a common skin and eye irritant for potential swimmers. Because chlorine and its related compounds are naturally drying to the skin, this effect is increased at high levels and often results in the discomfort of swimmers.

It is even possible to develop a temporary chlorine rash after swimming in overly chlorinated water, but this rash will fade away on its own over time.

Reduce Metal Staining

Another reason might be that you have metal staining on your pool surface. In this case, you will want to use a metal chelating solution to remove dissolved metals from your water.

These solutions typically require zero free chlorine in your pool to work properly, hence the need for a chlorine remover.

If you have high chlorine levels in your pool that are not going down on their own, you will want to use a chlorine neutralizer or remover.

These products remove the chlorine from your pool through a chemical interaction, eliminating the need for large volume water changes or the week-long waiting periods that are associated with allowing the chlorine to dissipate naturally.

How Do Chlorine Neutralizers Work?

Almost all chlorine neutralizers contain an active ingredient called sodium thiosulphate.

When introduced to your high chlorine pool, this sodium thiosulphate immediately reacts with both the free and combined chlorine compounds in your pool to form inactive compounds, lowering the amount of chlorine in your pool.

As they do react with combined chlorine, chlorine neutralizers are also effective at removing chloramines, which on their own cause a number of problems.

The resulting compounds that are formed after the use of sodium thiosulphate are harmless to both your pool and swimmers, making chlorine neutralizers a great option for fixing an over-chlorinated pool quickly.

Most of these products achieve full results in under six hours, allowing you to reopen your pool for regular activities.

Although there are other methods of lowering the high chlorine levels in your pool, using a chlorine neutraliser is by far the most cost-effective chemical treatment available, and it is also much more time-efficient than waiting for natural degradation of your chlorine to occur.

How To Use Chlorine Removers

Test Your Chlorine Levels

Before adding a chlorine remover to your pool, you will want to measure your chlorine levels as precisely as possible. This step is necessary in order to avoid using an incorrect dose of sodium thiosulphate in your pool.

If you tested your chlorine levels previously but not recently, they may have changed as natural degradation occurs. Because of this, we recommend that you test your chlorine levels again closer to the time you intend to add your chlorine remover.

As we mentioned earlier, ideal chlorine levels range from 2-4ppm. As a general rule of thumb, it is recommended that you only add chlorine removers to pools reading at 5ppm or above.

This rule is in place in order to avoid adding too much of this product, which could drop your free chlorine to zero and create a strong chlorine demand that will make it difficult to achieve any free chlorine for a while.

To test your chlorine levels, we recommend using a solution-based test kit rather than testing strips. While testing strips can make a great, cost-effective option, solution test kits are typically able to offer more accurate and more precise readings.

Calculate How Much Product To Add

When calculating how much product to add to your pool, you will need to use the chart provided by your product manufacturer. If you have not selected a product yet, we recommend the neutraliser produced by the time-trusted manufacturer Lo-chlor.

This chlorine neutraliser is highly concentrated and allows you to achieve results in as little as a few hours. In a pool of 50,000 litres, it only takes 50 grams of product to reduce chlorine levels by 1ppm when using Lo-chlor’s chlorine remover.

Be sure to add the correct dosage of sodium thiosulphate to your pool.

Too much sodium thiosulphate can cause low chlorine levels that will persist for several days despite how much chlorine you attempt to add, so it is best to start with a lower dosage if you are hesitant about how much to use in your pool.

Add And Circulate The Product

Most chlorine removers do not require mixing and can be added directly to your water by being dispersed around the perimeter of your pool while the pump is running. Alternatively, you may choose to broadcast this product over the surface of your pool if it is not windy.

It is important to follow any instructions given by your product manufacturer because different brands use different formulations and concentrations.

If specific steps are mentioned, these guidelines are often necessary in order to ensure safety and efficacy when using the product.

Retest Your Chlorine

After you have added your product and allowed your pump and filter to run for a few hours, or as otherwise advised, you will want to retest your chlorine. Ideally, your levels should now be within the appropriate range if a correct dosage was used.

If your chlorine is still too high, repeat the above process until your desired results are achieved.

If your chlorine is now reading too low, you have added too much sodium thiosulphate. Unfortunately, it will be fairly difficult to raise your free chlorine level now, as the residual sodium thiosulphate in the water will create a strong chlorine demand.

Use this chlorine calculator to work out how much to add.

After lowering your chlorine, your pool is typically ready for swimming. Unlike with other chemical methods of lowering chlorine, sodium thiosulphate is not known to cause changes in the other chemical properties of your pool, which saves lots of time and money.

Ways To Lower Chlorine Without A Neutralizer

While sodium thiosulphate is the most cost-effective solution to high chlorine levels, there are other methods of lowering them.

Although there is no homemade alternative to chlorine neutralisers that can be made with household chemicals, chlorine will slowly degrade over time when exposed to sunlight and water agitation.

In order to speed up this natural process, you can keep your pump running for longer hours and remove any sun covers from your pool to better allow for chlorine degradation.

You may also use hydrogen peroxide or ascorbic acid, which is otherwise known as vitamin C, to lower the chlorine content of your pool.

Before embarking on these alternative methods, it is important to note that the cost of these chemicals is likely to be much more expensive than using sodium thiosulphate.

Another downside of these products is that hydrogen peroxide and ascorbic acid also tend to mess with your pool’s other chemical levels, especially the pH and total alkalinity.

Because the use of these products requires achieving a specific pH before use and correcting your pH again afterwards, this process can be much more costly in the long-run.

We recommend sticking with sodium thiosulphate.


Chlorine neutralizers are a top choice among those looking to decrease their pool’s high chlorine levels.

Because these products work quickly and are not known to alter other aspects of your water’s chemistry, they make a great remedy to high chlorine levels when you are in a time crunch.

Do you have any questions about how chlorine removers work or how to use them in your pool? Leave us a comment, we’d love to help out!

Louis from Pool Advisor


A chemical engineer by trade, Louis is committed to debunking myths in the pool industry by explaining the underlying chemistry and making it accessible to all.