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Total chlorine is the amount of free chlorine plus combined chlorine in your pool water. The amount of chlorine in your water doesn’t automatically mean your pool water is clean. That’s because free chlorine is the amount of uncontaminated chlorine, and combined chlorine is the free plus contaminated chlorine in a pool.

An adequately sanitized pool has the right balance of chlorine. Many pool owners assume that adding chlorine tablets will make swimming more sanitary and safe. But a lot of chlorine in a swimming pool doesn’t clean your water.

Continue reading to learn how to balance your pool’s free, combined, and total chlorine levels!

What Are the Main Differences Between Total and Free Chlorine? 

Chlorine is the most common form of pool water sanitizer. While there are other options, such as bromine, chlorine is the most widely available and affordable option. To understand the difference between total and free chlorine, you need to understand how chlorine works.

Chlorine enters the pool water and reacts with the water, creating hypochlorous acid. This compound reacts with many particles and bacteria in the water, oxidizing them and forming hypochlorite.

After breaking the molecular bonds of these contaminants, the compounds join together and create chloramines. These chloramines produce the strong smell most people and pool owners associate with chlorine, but if this scent is too potent, it can indicate an issue with how your chlorine is working.

Terms like free chlorine, combined chlorine, and total chlorine refer to different steps along this chlorination process. The free chlorine levels of your swimming pool water refer to the fresh chlorine levels in your pool water.

Combined chlorine is the amount of chlorine in your water that has bound and reacted with other contaminants. These substances create a powerful chlorine smell and convert the sanitizing chemical into chloramines.

Test kits can show you your total chlorine which is the combined plus free chlorine levels in your water. Free chlorine differs from total chlorine in that it refers to the available sanitizing chlorine levels in the water. Total chlorine is a measurement of both available and used chlorine in your pool.

What is Total Chlorine? 

Total chlorine is the combined chlorine and free chlorine levels in your pool water. Ideally, your total chlorine will show your free chlorine levels surpassing the combined chlorine levels in the swimming pool.

The best results would read that there are zero combined chlorine molecules in the water. But this is unlikely to happen since it would indicate that there aren’t any bacteria or contaminants for your chlorine to break down.

If your combined chlorine level is too high, it can indicate that your free chlorine level isn’t sufficient. When the total chlorine level suggests that the combined chlorine level is higher than the free chlorine level, you might need to shock your swimming pool.

What is Free Chlorine? 

Free chlorine is the amount of available chlorine in the water to clean contaminants. Properly sanitized water needs to have sufficient free chlorine to kill bacteria and algae and dissolve oils.

Free chlorine needs to outnumber the combined chlorine level in your pool to properly clean the water. Free chlorine also removes excess combined chlorine so your pool doesn’t get too many chloramines.

Is Total Chlorine the Same Thing as Combined Chlorine? 

Total chlorine is not the same thing as combined chlorine. While the total amount of chlorine indicates how much-combined chlorine and free chlorine your water currently has.

Free and combined chlorine indicate how well your pool water is being sanitized. But total chlorine means how much free chlorine vs. combined chlorine you have in your pool. Combined chlorine levels refer only to the amount of chlorine reacting with the contaminants.

How Do You Test Your Total and Free Chlorine Levels? 

There are three primary types of test strips and chlorine testers to calculate the amount of total and free chlorine. While standard test strips are the most commonly used, there are also electronic and automatic testers.

Generally speaking, you’ll want to use these test kits to determine whether you need to sanitize your water. If the combined chlorine level is too high, it can indicate that you need to add shock to the pool water.


When measuring chlorine levels, it’s important to know where each variety of chlorine stands. Free chlorine refers to the amount of available sanitizer in your water. You’ll want to keep this level high and prevent getting the combined and total chlorine levels higher than they should.

If you need to lower your combined and total chlorine, then you’ll need to add water to your swimming pool. This is one of the only ways to restore your pool chemistry to normal levels.

If you want to learn more about balancing your pool water and keeping it clean, check out our article on proper pool care!


Is it Dangerous to Have High Total Chlorine Levels? 

It can be dangerous for you and your pool if chlorine levels are too high. This is especially true if your swimming pool has high combined chlorine levels.

Since this can indicate a lot of germs in the water, it’s not wise to swim in a pool with high amounts of combined and total chlorine.

How Do You Lower the Total Chlorine Levels in Your Pool? 

Chlorine dissipates under UV rays and heat. The best way to remove excess chlorine in the swimming pool is to not add chlorine and let the heat and rays of the sun do their job.

Adding fresh water with the hose is one of the easiest and most effective ways to rebalance the pool’s chemistry. To kill excess contaminants from the water, use a non-chlorinated shock treatment to lower your total chlorine level.

However, if your total chlorine indicates low levels, you should add chlorinated shock. Low total levels of chlorine mean your free chlorine isn’t high enough.

What is the Right Free Chlorine Level?

Ideally, you’ll keep your pool’s free chlorine levels between 1-2 parts per million. According to the CDC, free chlorine at 1-2 ppm should kill most dangerous compounds and bacteria. You should keep your free chlorine or bromine for spas and hot tubs between 3-4 ppm.

Is an Electronic Chlorine Tester Worth it?

Electronic chlorine test kits are a good investment but may not be necessary. Electronic chlorine testers are more accurate and easy to use than test strip kits. If you’re struggling to balance your water levels, you might want to invest in an electronic tester.

What Kind of Test Strips Are Best for Testing Chlorine Levels?

Paper or plastic test strips are the most common and easy to use. These test kits can show you the pH levels of your water and determine your free, combined, and total chlorine in the pool.

However, an electronic tester is the most accurate tool for determining the various chlorine levels of your water. If you need to know where your free, combined, and total chlorine levels stand, then you can use a liquid test kit, strips, or electronic testers. But electronic testers are the most accurate.