Free Chlorine vs. Total Chlorine

In order to keep your swimming pool clean and clear you will need to monitor the chlorine level of the water. Premium quality chlorine keeps your pool water safe and clean by eliminating bacteria without leaving cloudy water or residue behind. With regular use it will control algae, kill bacteria, and produce crystal clear swimming pool water. Focus chlorine is stabilized against the sun’s UV rays which break down chlorine.

You may have noticed your test strips will check for free chlorine and total chlorine, but there are actually 3 types of chlorine in your pool. Combined chlorine is the 3rd form of chlorine in your pool. So what is the difference between them?

Free Chlorine

• Free chlorine is the amount of chlorine in your pool that is available to sanitize the water
• Has not yet interacted with any contaminants in the water
• Most common chemical pool owners should test for
• Should measure between 1 and 3 parts per million (ppm)

Combined Chlorine

• Also known as chloramines
• The chlorine that has already been “used up” to sanitize the water
• While still found in the water its ability to sanitize is reduced

Total Chlorine

• The sum of Free Chlorine and Combined Chlorine in the pool water

Since the purpose of adding chlorine to your pool is to sanitize the water you want to make sure your free chlorine remains higher than your combined chlorine. Always make sure the free chlorine level is balanced in your pool water. Some test strips will only show the free chlorine level because that is what is most important in keeping the pool clean and clear.