Free Chlorine Vs Total Chlorine

Chlorine is the most commonly used ingredient every pool owner applies to disinfect pool water. 

But have you ever thought about the type of chlorine in your pool? Whether you think about it or not, we bet you heard these two terms- free chlorine and total chlorine.

There are many aspects to talk about when we discuss free chlorine vs total chlorine.

Whenever we say free chlorine, it means the proper amount of chlorine to mix with the pool water to sanitize or contaminate. But total chlorine indicates the combination of free chlorine and combined chlorine in the pool.

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Why Knowing Their Differences Is Important?

We have already mentioned that chlorine is to clean the pool water and kill the germs from it. But mainly, there are three types of chlorine that can be used in a swimming pool. They are:

  • Free Chlorine
  • Combined Chlorine
  • Total Chlorine

You must be thinking about why there are differences when all of them are just chlorine. Why do you need to know their differences? 

Chlorine breaks and reacts with different chemicals and to create hypochlorous acid and hypochlorite ions. These are used to kill germs.

Free chlorine works directly with those germs. But combined chlorine’s working mechanism is a bit different. It combines with the contaminants and then reacts with the remaining algae, bacteria, and germs. 

Total chlorine is the combination of free chlorine level and combined chlorine level. Therefore, if you don’t know the correct amount of total chlorine to apply in your pool, you may end up adding too much. It’s dangerous to swim in extra chlorinated water.

Free Chlorine

The meaning of free chlorine refers to the exact amount of chlorine that you will need to kill the bacteria and other microorganisms from the pool and sanitize it. Putting it another way, the amount of chlorine yet to be mixed with the pool’s chlorinated water is known as free chlorine.

Among all the types of chlorine, free chlorine plays the part of sanitizing the pool actively. It is called free chlorine because it can freely interact with other chemicals and microorganisms like bacteria, algae, fungi, etcetera. 

The free chlorine removes these harmful things effectively from your pool and can off-gas them into the atmosphere. The chlorine also reacts with the pool water and forms hypochlorous acid.

The acid further reacts with oxygen to form hypochlorite, which is an active ingredient of bleach. 


Adding free chlorine is a straightforward process. Whenever you feel that you need to clean the contaminate of the pool water, you can add free chlorine. It is a swift process to remove all the germs.

Even to raise the chlorine level now and then, you can use free chlorine. The chlorine level has to be between 1 ppm to 3 ppm. You can also add them in daylight as chlorine can vaporize quickly. 


You have to be careful while adding the free chlorine. The reason is that excess chlorine is harmful to your skin. Also, free chlorine doesn’t work against the contaminants. It only reacts with microorganisms.

Total Chlorine

If we want to simply put the idea simply, total chlorine is merely the summation of free chlorine and combined chlorine. It’s mainly the intermediate product or the contaminants created while removing the germs from the pool.

Total Chlorine = Combined Chlorine ( CC) + Free Chlorine (FC)

By testing the total chlorine level, you can estimate if there would be any need for free chlorine or combined chlorine. 

Suppose the level of free chlorine and total chlorine of your pool is the same. It means there is no combined chlorine remaining in the pool. Also, you can estimate that no other chlorine is to be added to the pool.

But if the level of total chlorine is higher than free chlorine, then the difference of these defines the level of combined chlorine. It would be best to keep free chlorine higher than the combined level if you want to sanitize your pool properly. 


The total chlorine can deal with the germs as well as the contaminants that come as a residue from the reaction with microorganisms.

When the total chlorine level gets higher than free chlorine, it will automatically create a combined chlorine level and deal with the contaminants in the pool.

Typically, you will notice that free chlorine level and total chlorine level have a comparative approach. Therefore, you won’t have to worry until the total chlorine gets low.


If the total chlorine level gets higher than the free chlorine level, then the number of contaminants will increase, and the pool’s environment will be polluted.

Suppose your pool water has too many algae in it. Will total chlorine level help then? No, it won’t help if you raise the total chlorine level.

As it requires two types of chlorine levels to increase total chlorine, it’s always a more complicated process.

Free Chlorine Vs. Total Chlorine: Which One Is Suitable to Use?

Free chlorine is just about getting rid of the germs and cleaning the pool water. But in total chlorine, it includes the combined, which means the contaminants. 

Too many contaminants make the pool environment inappropriate for swimming. Proper sanitizing is not possible without lowering the combined chlorine level.

Therefore, we can say that free chlorine is more suitable to use instead of total chlorine. 

Also, if you use the total chlorine, you have to maintain its level higher than free chlorine. Otherwise, there will be problems, which might lead you to shock the pool now and then. 

To conclude the decision, using free chlorine is definitely a better option than using total chlorine.

Free Swim!!!

There is a saying that free chlorine means free swim. Well, it is not entirely wrong. 

With free chlorine, you can swim anytime in your pool. All you need to do is adjust the chlorine level at night, and your pool should be ready by morning. But make sure that you use the exact amount of chlorine and keep it sanitized all the time. 

It’s common sense that an unsanitized pool is not a place you want to swim. Again, the contaminants from total chlorine make foams and other residues that might not be recommendable to everybody. Thus, use free chlorine for free swimming.

Bottom Line

After the discussion, it should be clear to you which one better for your swimming pool. Regular swimming is a healthy habit for anybody. Therefore, maintaining the chlorine level is crucial if you don’t want an interruption in your routine. Our inclusive take on free chlorine vs. total chlorine should now help you better understand chlorine levels and which one to maintain. Swim safely and have the best of times in your pool this summer!

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