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.
Combined, Total, and Free Chlorine
We’re focusing on total free chlorine here, but there are actually three types of chlorine If you click this link and make a purchase, we earn a commission at no additional cost to you. :
- Free Chlorine – This is the chlorine you test for If you click this link and make a purchase, we earn a commission at no additional cost to you. 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, the ideal level being 3 ppm.
- 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 is the sum of combined and free chlorine.
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Breaking Down the Differences in Total and Free Chlorine
To help explain the differences, take a look at this simple formula for chlorine:
FC + CC = TC
When you add chlorine to your pool, it reacts with the water to form hypochlorous acid and hypochlorite ion. These compounds together form what we call free chlorine.
Once this chlorine begins to react with the contaminants in the water, such as nitrogen and ammonia, it becomes combined chlorine.
In this state, the chlorine isn’t as effective at sanitizing compared to free chlorine. Your goal is to make sure your pool is sanitized. You want to make sure your free chlorine levels stay in check.
For example, if your free chlorine levels and total chlorine levels are the same, then there’s no combined (or used chlorine) in your water. If your total chlorine level is higher than the free chlorine level, the difference of the two are the combined chlorine levels.
To make sure your pool is sanitized, your free chlorine should remain higher than your combined chlorine.
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Time for Some Simple Pool Math
I know, you didn’t expect to have to do math when you bought your pool. But it’s critical to maintain high water quality.
These numbers will help you determine exactly how much chlorine to add for it to continue doing its job of destroying bacteria and any other contaminants in the water.
If you notice your combined chlorine levels going up, you know the time has come to rebalance the sanitizer in the water by adding extra chlorine to your pool. If the levels are low, then you may not need to do anything at all that day.
Did This Help Clear up The Difference Between Total and Free Chlorine?
While it can be confusing at first, understanding the differences between free and total chlorine can help you take care of your pool. Sanitation of your pool water is essential. It keeps the water clean and clear and ensures that the water is safe for swimming.
Now that you know what each of them actually are, you will be able to more easily recognize what you need to do in order to keep the sanitizer levels where they should be so your water stays clean, clear and safe all summer long. So break out your water testing kit and test your water for its chlorine levels.
Happy Swimming!
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Click here to learn moreRecommended Reading The Definitive Guide to Using Cyanuric Acid (Pool Stabilizer)
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Liquid Chlorine or Chlorine Granules: What’s the Difference?
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The Definitive Guide to Using Cyanuric Acid (Pool Stabilizer)
Also called pool conditioner or chlorine stabilizer, cyanuric acid is vital to your pool's chemistry. Learn how and why to include it in your water care.
How to Shock a Swimming Pool
When's the last time you shocked your pool? If it's been a while, you're laying out a doormat for contaminants. Keep them out with a good pool shock.
How to Cure Chlorine Demand and Chlorine Lock
Sometimes, when you have a lot of debris and other organic material in your pool, it may require chlorine to handle it. This is called chlorine demand.
How to Add Chlorine Tablets to Your Pool
Should you switch from granules to chlorine tablets? Yes, if you're looking for an easier, more effective way to sanitize your pool. Find out why.
Automatic Pool Chlorinators Vs. Putting Pucks In Your Skimmer
Should you put chlorine pucks in your skimmer or use an automatic chlorinators to dispense? We can all agree to at least get rid of the floater.
Liquid Chlorine or Chlorine Granules: What’s the Difference?
Is there any difference between liquid chlorine and chlorine granules? Read more to learn the differences so you can decide what's best for your pool.