What is the Difference Between Free Chlorine and Total Chlorine?

The difference between free chlorine and total chlorine lies in their ability to sanitize contaminants in water, such as in swimming pools or hot tubs. Here are the key differences:

• Free Chlorine: This refers to the amount of chlorine that has not yet combined with contaminants and is available to sanitize the water. Free chlorine is added to clean and sanitize the water, and it is the value you typically test for in pool maintenance.
• Total Chlorine: This is the sum of both free chlorine and combined chlorine. It represents the total amount of chlorine present in the water, including the chlorine that has already been used up for sanitization.
• Combined Chlorine: This refers to the chlorine that has combined directly with contaminants, such as nitrogen and ammonia, making it less effective at sanitizing compared to free chlorine.

To maintain a properly sanitized pool, it is essential to test for both free and total chlorine levels regularly. The goal is to ensure that the free chlorine levels remain higher than the combined chlorine levels. If the total chlorine level is higher than the free chlorine level, the difference between the two is the combined chlorine level.

Comparative Table: Free Chlorine vs Total Chlorine

The difference between free chlorine and total chlorine lies in their composition and role in water disinfection. Here's a table summarizing the differences:

Free chlorine is the active chlorine available for disinfection, while total chlorine includes all forms of chlorine in the water, which is the sum of both free chlorine and combined chlorine. Measuring both free and total chlorine levels is recommended for optimal pool water maintenance.