How to Lower Chlorine Levels in Your Pool

Chlorine is a chemical used to kill germs. It destroys germs from saliva, urine, feces, and other substances, which makes it a very useful product for disinfecting swimming pools.

Therefore, as a pool owner, it’s important to check your pool regularly to ensure it’s chlorinated to protect everyone using it.

That said, did you know that too much chlorine is harmful?

Health experts warn that excessive exposure to chlorine can cause asthma bouts, rashes, nose and throat pain, coughing, and eye irritation. According to the California Department of Pesticide Regulation, 534 people have gotten sick in the last 10 years due to overexposure to excess chlorine while swimming. That number is very low compared to the number of folks swimming every year, so don’t fret too much.

However, it’s important to follow the manufacturer’s instructions when chlorinating your swimming pool. Your pool chemistry can change over time, 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, as well as what causes high chlorine levels. The ideal range for your chlorine levels should be 3 parts per million (ppm).

What Causes High Chlorine Levels?

Several reasons could cause your pool’s chlorine level to increase above the recommended range. One of the most common being when too much chlorine is added, especially after an eventful day.

Chlorine tablets can be another common reason. They’re handy when you expect to be away from home for an extended period, but adding even just a little too much can impact your pool’s condition.

Meanwhile, 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. When these two chemicals aren’t correctly balanced, it causes a rise in the pool’s chlorine level.

Moreover, if your pool is located under a shed or indoors, it will only get minimal sunlight. Unfortunately, that chlorine won’t break down as fast as it would under direct sunlight. Instead, it’s likely that the rate at which you’re adding chlorine to your pool won’t be the same rate at which it’s burning off.

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

Chlorine in the pool is made of two compounds. One is the chlorine used to fight microorganisms and bacteria. The second is chloramine, which is the result of the chlorine combined with organic matters that characterize a chlorinated pool’s odor.

However, the fact that you can smell the amount of chlorine is a mere myth. You could use symptoms such as irritated eyes and skin to tell if your pool is over-chlorinated. 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

Chlorine, when at the right level, is harmless to humans. Unfortunately, at extreme levels, it can pose health risks to anyone exposed to it.

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. One extreme effect, though rare, is chlorine poisoning, which usually requires immediate medical attention.

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

Strategies for Lowering Chlorine Levels

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 severe. Still, if it’s only a little high, then the sun is usually a dependable solution.

All you have to do is expose your pool water (with the pool cover off) to the sun for a few days. 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 effective in cases where the pool is located indoors.
  • 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 chlorine slightly above normal.

Why? Well, it’s all about taking advantage of chlorine’s main purpose being to sanitize your pool water. By inviting people over, you’ll increase the number of contaminants and potentially reduce the pool’s chlorine level.


  • It’s free
  • No use of chemicals


  • Not effective if the level of chlorine in the pool was 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 perform a pool test 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 afterwards

4. Heat The Pool Water

Heat indirectly affects the chlorine level in your pool. When temperatures rise, bacteria will proliferate and increase the amount of chlorine sanitizing the water.

If you can heat your pool, raise the temperature to about 90oF to 100oF above what’s normal for your pool.


  • It’s free
  • No chemicals involved


  • Only applicable in heated pools
  • Increases your energy bill

5. Use Sodium Thiosulfate

The trick behind using sodium thiosulfate to balance out the chemical levels in your pool is that it acts as a chlorine neutralizer. Depending on the chlorine level and capacity of your pool, different doses and treatments may be required.

Besides sodium thiosulfate, there are various chlorine neutralizers you can use, 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 be careful not to add too much.

Over-neutralizing the chlorine might bring the level down too low 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

6. Use Hydrogen Peroxide

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

For best results, try to use hydrogen peroxide specifically designed for pools. If you opt for normal home cleaning products, which 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

7. 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 of lowering chlorine levels because while ascorbic acid neutralizes the chlorine in the pool, reducing the chlorine level, the reaction between ascorbic acid, and chlorine is fast and the results are non-hazardous to humans.

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


  • Effective in cases where chlorine levels are extreme and need to be greatly 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 impact that high chlorine levels have, and what causes them, you’re one step closer to making your pool safer. Remember, some of the best ways to lower the chlorine levels are to heat your pool, drain and dilute the water, or to use another chemical, like hydrogen peroxide, to help mitigate the chlorine. We hope you find this information useful in helping you to ensure your pool is safe for your family and friends to enjoy a swim.

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