Why Do Free Chlorine vs Total Chlorine Levels Matter in Swimming Pools?

Why Do Free Chlorine vs Total Chlorine Levels Matter in Swimming Pools?

The Difference Between Free and Total Chlorine

From Swim University

Most people when they are swimming in an inground pool are congnizant of one aspect of water chemistry: Chlorine Level.  What people don’t realize is that this seemingly simple measure is actually quite complicated.  It takes an amateur chemist to understand water balance, and all of the various factors that can affect it in swimming pools.  This post by Matt Giovanisci of Swim University, however, attempts to explain the components of chlorine within that complicated mixture.  

Here is an excerpt from the post:

The chlorine levels in your pool are one of the most important measurements you must keep track of all the time. After all, it’s what sanitizes your pool.

There are different types of chlorine, and it confuses pool owners. What they should be testing for in their pools?

Pool experts throw around terms like “free chlorine” and “total chlorine.” This just leads to confusion. So, let’s stop and explain the differences between free and total chlorine. Because once you understand, you will then be able to better track the levels in your pool.

3 Types of Chlorine

We’re focusing on free and total chlorine today. But there are actually three types of chlorine. They are:

Free Chlorine – This is the chlorine that you usually test for in your pool water. This chlorine is available to sanitize your pool. Your pool should have between 1 and 3 parts per million (ppm) in the water.
Combined Chlorine – This is chlorine that’s been used up by the sanitation process of the water. While it’s still in the water, its ability to sanitize is reduced compared to free chlorine.
Total Chlorine – This type of chlorine is the sum of both free chlorine and

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