How to Lower the Chlorine Level in your Pool: 5 Simple Solutions

Want to learn how to lower the chlorine level in your pool? 

We’ve got you covered with these 5 simple solutions that will have you back to swimming safely in no time!

woman swimming in pool with lower chlorine levels

So you’ve opened your pool, cleaned the patio, bought some great patio furniture and are ready to swim!

You even managed to get rid of all the wasps and frogs invading your pool area.

But what do you do if after all of that, your chlorine levels are too high?

What are some quick ways to lower the chlorine level in your pool so that you and your family can safely enjoy it?

Keep reading below to check out 5 simple solutions to test and lower the chlorine level in your pool.


Safety Warning

The first thing you should know is that it’s never safe to swim in a pool that has chlorine levels that are too high or too low.

You can get seriously sick.

Before reading on, understand that you need to keep swimmers out of your pool if it currently has a high chlorine level.


Rather Watch than Read?

Check out this great video from Clean Pool & Spa detailing how to lower the chlorine level in your pool.

Otherwise read on below for step-by-step instructions!


What Does Chlorine in a Pool Do?

If you didn’t know, chlorine is a chemical that goes into your pool to make the water safer. Its main function is to kill germs like E. coli and salmonella.

That means that you can enjoy swimming in your pool without being exposed to bacteria.

Chlorine also kills bodily fluids and sweat that make their way into the pool. Part of that means neutralizing odors that might otherwise linger in the water.


How Does Chlorine in a Pool Work?

The process works just like adding a mixer to a drink. You want the ratio to be perfect so the drink tastes good.

In this case, the “flavor” is how safe your pool is to swim in. A pool with no chlorination is very unsafe.

You start adding chlorine and you change the parts per million (ppm) of chlorine.

1.0-3.0 ppm is the ideal range for free chlorine in your pool.

Three ppm is on the high end in most cases. That means if you look at a million particles in your pool’s water, less than three of them will be chlorine.

When the chlorine interacts with your pool’s water, it breaks down into a bunch of different chemicals.

The big chemical you care about is hypochlorous acid. This is the thing that does the killing. Don’t worry though, it’s less harmful to us than the bacteria that it kills.

However, it’s important to understand what free, combined, and total chlorine is. When you measure the chlorine in your pool, these are three results you will care about.


What is Free Chlorine?

If you imagine an NBA game, free chlorine is the bench of players. They’re waiting for their opportunity to play the game, but they’re not doing anything right now.

Free chlorine is how much chlorine is in your pool that has the ability to kill germs.

These particles are not actively killing germs, nor are they activated yet. Once they come in contact with organic material though, like bacteria, then they will activate and do their job.


What is Combined Chlorine?

Combined chlorine is also called chloramine.

Chemically, it’s the combination of chlorine particles and micro-organisms like bacteria or body fluids.

In other words, combined chlorine is the particles that are actively working and have already attacked germs.

Going back to the NBA analogy, you can think of combined chlorine as the five guys on the court.

You don’t want combined chlorine in your pool. This is the leading reason to shock your pool. In fact, that “chlorine smell” is due to combined chlorine.


What is Total Chlorine?

Total chlorine is simply the combination of free and combined chlorine.

If you count how many NBA players are on the bench and add it to how many are on the court, you get your total value.


Misconceptions About Chlorine and Pool pH

There is an interesting misconception a lot of pool owners have.

Some people think that the purpose of adding chlorine is to raise the pH of your pool so it’s safe to swim in.

Actually, pH doesn’t determine whether or not bacteria are going to live or die.

The chlorine particles are what’s killing the germs. Chlorine itself has a pH around 14, but it won’t change the pH of your water at all.

The results of chlorine are almost equal parts of hypochlorous acid (acid) and sodium hydroxide (base).

When the acid is introduced to UV rays, it becomes hydrochloric acid. The combination of this acid and base result in a net-zero change in your water’s pH.

pool chemicals to lower chlorine level


Understanding pH

Time for a quick flashback to high school chemistry.

pH is how acidic or basic your pool’s water is. Our bodies are pretty particular about what range is comfortable. Contact with something that’s too acidic or basic will burn your skin.

You can think of pH as an environment where things happen. A lot of chemicals need a certain pH to even work – and chlorine is no exception.


The Right pH for Chlorine

The perfect pH for chlorine is between 7.4 and 7.6.

Going above 8.0 will drop its effectiveness by more than 20%. That’s all for pH in this guide – everything else is going to be about chlorine and your water.


How to Measure Chlorine Levels in a Pool

The only real way to measure chlorine is to use a test kit specifically made for your pool. Keep in mind, this is a chlorine test, not a pH test.

However, most kits, like this one, will also easily measure pH, alkalinity, and other levels in your water.

These kits will have step-by-step instructions on the packaging that should be followed. The following is a general rundown of the process.


Using a Chlorine Test Kit Strip

The test strip kit will have special strips of paper in it. With clean and dry hands, grab the strip.

Submerge it in your pool until you’re about elbow-deep in water. Keep it there for a few seconds depending on your specific test kit. Read the instructions for an exact time.

Take the strip out of your pool, lay it horizontally with the color pads facing upwards, and make sure it’s not in contact with direct sunlight. When the color settles, take it to the color chart provided with your test kit.

The color chart has a range of different chlorine values. You’ll want to make sure you’re within the acceptable range.

Some strips, like this one, test free, combined, and total chlorine, so make sure you really look at your test results.

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Using a Chlorine Test Tube Kit

Instead of a strip, some kits, like this one, use chemical reagents to test a sample of water directly.

se a special tube. You fill the tube to the line with pool water. elbow deep in your pool, again, and then follow the instructions that come with the test kit.

Again you will use a color guide to measure the exact amount of chlorine in your pool.

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Why Does Chlorine Level Matter?

Achieving the perfect level of chlorine is one of the most important parts of owning a pool. Not enough, or too much, chlorine will get your swimmers sick.

If there’s not enough, then the harmful bacteria in the water isn’t getting killed.

Too much chlorine can irritate the swimmer’s eyes and skin and even lead to respiratory illness.

Extreme amounts of chlorine can even lead to chlorine poisoning which, yes, is as bad as it sounds.


The Ideal Chlorine Level

If you want a healthy pool, then you need to stick between 1.0 and 3.0 ppm of free chlorine.

This ensures that bacteria are getting killed without the harmful effects of over-chlorination.


How Often Should You Add Chlorine to your Pool?

The frequency of adding chlorine depends on a few factors.

If you use the pool often, have lots of bugs and leaves in the pool, and live in a sunny area of the world, you’ll need to add chlorine more regularly.

Unless you have a saltwater chlorine generator, the best advice would be to use an automatic pool chlorine dispenser and chlorine tablets.

This almost completely eliminates the need to routinely add chlorine.

It will slowly dissolve over time, and all you’ll have to do is check the dispenser from time to time to ensure there are enough tablets.

The same is also true for people who put their tablets in their pool’s skimmer basket.


What Causes the Chlorine Level to Get Too High in a Pool?

One of the more common reasons for high chlorine levels is that you just overdid it with a shock treatment.

Alternatively, adding too much cyanuric acid to your pool causes high chlorine levels.

Clorox Pool&Spa Chlorine Stabilizer 4 lb

Cyanuric acid prevents chlorine from being lost due to UV exposure and while some is good to help you retain it in the water and ultimately save money on chlorine, like everything else in chemistry, too much is a bad thing.

Also, if your dispenser is not working correctly, you might find yourself coming home to an over-chlorinated pool.


5 Ways to the Lower Chlorine Level in a Pool

Now let’s talk about the exciting stuff.  These are the 5 ways to quickly lower the chlorine level in your pool.

Determine which approach works best for you. This might mean some trial and error, but you have plenty of options to choose from!

No matter which method you use, you shouldn’t go back into the pool until you confirm the chlorine is back to a safe level.

That might mean doing a test every 12 or 24 hours to keep track.


#1: Add Chemicals

There are three chemicals that you can consider using if you want to lower the chlorine in your pool.

All of them use a little bit of chemistry to break down and remove chlorine particles. Namely, you can use ONE of the following:

  • ascorbic acid
  • sodium thiosulfate
  • hydrogen peroxide.

For ascorbic acid, 32 oz in 10,000 gallons of water will drop your chlorine level by 9 ppm.

Sodium thiosulfate needs 2 oz in the same amount of water for a drop of 1.0 ppm.

Hydrogen peroxide required a gallon per 10,000 gallons of water to lower your chlorine level by 55 ppm.

It all depends on how severely over-chlorinated your pool is as well as the size of your pool.

If you’re using chemicals to treat the chlorine level in your pool, you need to close your pool. Never add chemicals to your pool when people are in it.

Also, make sure that you read the label of the chemical and very carefully measure how much you’re putting in the pool.

Lastly, always dilute any chemicals you are adding to your pool in a bucket of water first and remember the following:

Always add chemicals to water, NOT water to chemicals to prevent dangerously concentrated splashback.


#2: Stop Adding Chlorine

It might seem like a no-brainer, but the solution is so easy that many people overlook it. If you want your chlorine levels to drop, stop adding chlorine.

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This means removing the chlorine tablets from your skimmer, filter, or dispenser.

If you keep your supply of chlorine alive, you’ll never be able to get ahead of it.

You’re fighting an uphill battle until you stop adding chlorine to your pool and tackle the problem.


#3: Let the Sunshine Work

UV rays do a good job at killing chlorine. It’s one of the reasons why you need to add extra chlorine to your pool.

sunny pool

It can also be used to your advantage if you have added just a little too much chlorine.

Remove any chlorine dispensers from the pool and stay out of the pool for a few days and check the levels every day to monitor the levels.

This technique should only be used if your chlorination levels are just slightly too high. Chlorine levels that are way too high would take a long time to stabilize with sunshine alone.


#4: Swimming (If Levels are Safe)

Another way to use up some of that chlorine is by simply swimming around your pool. If your pool is below 4.0 ppm, it’s still safe for humans to swim in.

kids swimming in a pool with safe chlorine levels

This option will help you slightly lower your chlorine levels and make the pool more comfortable.

Just like sunlight, chlorine’s interaction with us is another reason that you have to add chlorine.

It reacts with bacteria and fluids from our bodies. You can use this to help you if you’re looking to minimally lower the chlorine level in your pool.


#5: Replace Your Pool’s Water

Dilution is ultimately the best remedy for balancing your chlorine levels f they are much too high.

You have to realize that your pool’s pH, calcium hardness, alkalinity, and other properties will also change with this option. You’re basically getting a fresh start.

a hose pouring fresh water inot a pool to lower the chlorine level

This option can be expensive and takes a while. You should drain around 1/4 of your pool’s water and then fill it back up.

Once the new water has thoroughly circulated for a few hours, test the water at an elbow deep depth once again.  Repeat the process until your chlorine levels are back in the ideal 1.0-3.0 ppm range.

You’ll now also have to go through the steps to balance and equalize all of the other water properties in your pool such as pH, alkalinity, hardness, and cyanuric acid levels.


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