How to Lower The Chlorine Level in Your Pool

Chlorine is a chemical used to make water safe for swimmers by killing germs, harmful bacteria, and other microbes. Therefore, as a pool owner, it’s important to check your pool regularly to ensure it’s appropriately chlorinated to protect everyone using it.

However, following the manufacturer’s instructions is important when chlorinating your swimming pool. It is easy to accidentally pour too much chlorine into your pool and over-chlorinate the water. So what do you do if there’s too much chlorine in your pool?

Read on to learn how to lower chlorine levels in your pool and what causes high chlorine levels.

Main Takeaways

  • Chlorine can easily be over-added to pool water by adding too much shock or an improper balance of muriatic acid.
  • High chlorine levels can affect swimmers’ respiratory system, cause skin irritation, and damage pool equipment.
  • Chlorine can be balanced by slightly draining the pool, allowing the pool to be exposed to the sun for an extended time, and using a chlorine neutralizer.

What Causes High Chlorine Levels?

Several things could cause the chlorine level in your pool to exceed the recommended range of 3 parts per million.

The most common reason for this is pool owners accidentally adding too much chlorine to the water. If you shock the pool, you may have miscalculated the amount of chlorine to add. Or, if you are using chlorine tablets for your pool, you may have added one too many.

If your pool is located under a shed or indoors, it will only get minimal sunlight. Unfortunately, that means the chlorine won’t break down as fast as it would under direct sunlight. This is also the case for regions that do not get a lot of direct sunlight throughout the year. Likely, the rate you’re adding chlorine to your pool won’t be the same rate at which it’s burning off.

And finally, an improperly balanced combination of cyanuric acid and chlorine can also cause a rise in the pool’s chlorine level. Cyanuric acid is a chemical used to protect the chemical structure of chlorine by reducing the rate at which it breaks down under the sun.

How to Tell If Your Pool’s Chlorine Level Is High

The rumor that you can smell the amount of chlorine is a myth. But you can certainly tell if your pool is over-chlorinated by feeling the effects on your body through irritated eyes and skin. Thankfully, there are safer and faster ways to check the amount of chlorine in a pool.

Use a pool water testing kit! For example, you could use a DPD (Diethyl Phenylenediamine) kit to measure the amount of free chlorine in your pool. Alternatively, you can use an OTO (Orthotolidine) test kit to estimate the total amount of chlorine in your pool, both the free chlorine and chloramines, to get a more accurate read.

Risks of High Chlorine Levels

At the right level, chlorine is harmless to humans. However, unfortunately, it can pose health risks to anyone exposed to it at extreme levels.

The most common result of a pool with high chlorine levels is discoloring. This can lead to your brand new bathing suit fading too fast. Since chlorine can damage colors, it can even affect recently dyed hair.

Some common health issues caused by exposure to high levels of chlorine include:

  • Respiratory illness such as asthma due to the excess chlorine vapor formed on the surface of the pool
  • Eye irritation and over-dilated blood vessels in the eyes, for those of you who prefer swimming without goggles
  • Dry skin and hair
  • Skin irritation characterized by a red rash with raised, itchy bumps

Typically, these symptoms of high chlorine levels clear up after a few days or weeks. Though rare, one extreme effect is chlorine poisoning, which usually requires immediate medical attention.

Besides health concerns, excess chlorine levels could eventually damage your pool equipment and pool cover.

How to Lower Chlorine Levels In Your Pool Fast

Depending on the pool’s chlorine level, you can use different methods to lower it. Below are the seven most effective ways to reduce the chlorine level in your pool to get in that 3 ppm sweet spot.

1. Use the Sun

Using sunlight is the easiest way to regulate chlorine levels in your pool. That said, it likely won’t do any good if chlorine levels are severely high. But the sun can be a great solution if the levels are only a little over the ideal limit.

If you have a pool cover, leave the pool uncovered for a couple of days, exposing the water to the sun.

The logic behind this is that ultraviolet (UV) light from the sun naturally breaks down chlorine, reducing the chlorine level in your pool to a safe level.


  • It’s free
  • No use of chemicals


  • It’s not practical for indoor pools
  • It may take a while

2. Pool Party

It may sound odd, but inviting your friends and family for a swim can be a great way to counteract above-normal chlorine levels. Just make sure to do this only if the chlorine level is slightly above normal. Otherwise, the high chlorine levels could harm your pool patrons.

So how does this work? Well, it’s all about taking advantage of chlorine’s primary purpose, which is to sanitize your pool water. Inviting people over will increase the number of contaminants and potentially reduce the pool’s chlorine level.


  • It’s free
  • No use of chemicals


  • Not practical if the level of chlorine in the pool is at extreme levels
  • Might irritate some of the swimmers

3. Drain and Dilute the Pool Water

Diluting your pool is an effective option if the chlorine level only needs to be reduced slightly.

To dilute your pool, you’ll have to drain some water from your pool and replace it with fresh water.

It’s important to test the water for all other chemical levels after doing this since you’ll be draining other chemicals alongside the chlorine.


  • It’s free
  • No use of chemicals


  • Increases your water bill
  • Rebalancing of other chemicals may be necessary afterward

4. Use Sodium Thiosulfate or Other Chlorine Neutralizers

Sodium thiosulfate balances the chemical levels in your pool and acts as a chlorine neutralizer. Depending on your pool’s chlorine level and capacity, different doses and treatments may be required.

Besides sodium thiosulfate, you can use various chlorine neutralizers, such as sodium metabisulfite, sodium sulfite, or sodium bisulfite. By and large, sodium thiosulfate is the most commonly used.

When adding the chlorine neutralizer, it’s important to avoid adding too much.

Over-neutralizing the chlorine might lower the level to the point that it fails to fulfill its purpose of fighting contaminants.


  • Highly effective method
  • Cost-effective


  • Significantly lowers the pH of your pool
  • Results take time

5. Use Hydrogen Peroxide

Hydrogen peroxide is a pool chemical oxidizer, which will break down chlorine through a series of chemical reactions.

For best results, use hydrogen peroxide designed explicitly for pools. If you opt for everyday home cleaning products that contain small amounts of hydrogen peroxide, you may find that they are less effective.

Before using hydrogen peroxide, test the pool’s pH and ensure it’s higher than seven for maximum effectiveness.


  • Cost-effective
  • Gives immediate results


  • Lowers your pool’s pH
  • Less effective if your pool’s pH is below seven

6. Use Ascorbic Acid

Using ascorbic acid (also known as vitamin C) is another means to reduce chlorine levels in your pool.

Most pool owners opt for this method to lower chlorine levels because the reaction between ascorbic acid and chlorine is fast, and the results are non-hazardous to humans.

However, ascorbic acid will decrease the pool’s pH when used in low alkaline waters.


  • Effective in cases where chlorine levels are extreme and need to be significantly reduced
  • Chemicals used are non-hazardous


  • Costly depending on your pool’s size
  • Requires large doses to ensure effectiveness

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Wrapping Up

Now that you’ve seen the causes and impact of high chlorine levels, you’re one step closer to making your pool safer. Some of the best ways to lower the chlorine levels are to heat your pool, drain and dilute the water, or use another chemical like hydrogen peroxide to help mitigate the chlorine. I hope you find this information useful in helping you to keep your pool safe for your family and friends.

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