Free Chlorine vs. Total Chlorine: What’s the Difference?

Free Chlorine vs. Total Chlorine

Chlorine is the most crucial compound for cleaning swimming pool water. When you add it to the pool, the free chlorine forms hypochlorous acid that then kills bacteria, germs, and other disease-causing microbes in the water.

Hypochlorous acid works by destroying the cell walls and oxidizing the microorganisms to render them inert and harmless.

That said, there are 3 different types of chlorine that you need to know about before you start adding it to your pool: free, combined, and total chlorine.

What is Free Chlorine? 

Free chlorine is the amount of chlorine available in the pool and is ready to eliminate or neutralize the contaminants in the water. This chlorine is yet to bind with the contaminants, and it is vital to monitor its levels keenly as it determines whether any harmful organisms in the pool are oxidized.

What is Combined Chlorine? 

Combined chlorine will develop in the pool water when the free chlorine binds with the contaminants as it neutralizes them. Chlorine in this form can sometimes also be referred to as chloramines. An adequately sanitized pool should not contain any combined chlorine, and keeping a good level of free chlorine in the pool is the best way to ensure this.

What is Total Chlorine? 

Total chlorine is all the chlorine present in the pool, meaning it is free chlorine plus the combined chlorine. Basic chlorine test kits and strips will typically show you the total chlorine in the pool as they cannot tell the different types apart. Also, a well-sanitized pool will not have any chloramines (combined chlorine). Meaning total chlorine will be equal to free chlorine.

How to Test Chlorine in Pool Water 

You can use either chlorine test strips, chlorine testing kits, or a digital chlorine sensor. Chlorine test strips like the JNW Direct Pool and Spa Test Strips are the cheapest and easiest method of testing chlorine, but they do not provide detailed information on the different chlorine types.

An electronic chlorine tester like the Solaxx MET01A SafeDip Digital Test Meter will give you the most accurate results. These electronic testers will provide you with the chlorine measurements in ppm (parts per million) and not just estimates.

Safe Chlorine Levels for Pool Water 

A good pool water test kit should help you determine whether your chlorine levels are within safe limits, but you still need to know the actual amounts to target.

That said, a safe level of free chlorine is between 1.0 and 6.0 ppm, but keeping the level at between 2 and 4 ppm is recommended.

Pool water with combined chlorine levels under 0.5 ppm is still safe, but it is even better to have the level below 0.2 ppm. The total chlorine level should be the same as free chlorine for a pool that is in good condition.


Chlorine is an important chemical when it comes to keeping your pool clean and sanitized. It is essential to know the different types of chlorine and make sure you maintain them at the recommended levels to keep the pool safe and clean.

By regularly sanitizing your pool and keeping track of the different chlorine types through regular measurements, you should have an easy time maintaining our swimming pool.

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