Total Chlorine Higher than Free Chlorine

Free chlorine residual should always remain higher than Combined chlorine residual during Daily testing and monitoring of Chlorine and along with your pool’s pH are the most critical parameters for the maintenance of a swimming pool to keep troubles away. What happens if total chlorine is higher than free chlorine?

Free Chlorine (FC) reacts with pool H2O first as Hypochlorous acid 60 to 100 x’s more effective at oxidizing microorganisms than the next stage hypochlorite ion which combines with ammonia making chloramines tested as Combined Chlorine (CC) a lesser disinfectant added to Total Chlorine (TC) residual.

Using Chlorine to disinfect your swimming pool is a reliable way to control contaminants that come in contact with your pool’s water every day as long as you keep the right chlorine residual standing guard. Keep it uncomplicated! Know the difference between the types of Chlorine.

What is Free Chlorine


Free Chlorine (FC) is the best type of Chlorine that will kill microorganisms and sanitize your swimming pool. Your pool should have between 1 and 3 parts per million (ppm) available in the water.

Free chlorine is the chlorine that is available to destroy pathogens in the pool water. This type of chlorine is powerful and has not yet interacted with any contaminants in the water.


What is Total Chlorine


Total Chlorine (TC) is Combined chlorine(CC) + free chlorine(FC)  Once free chlorine is weakened it combines with ammonia to form chloramines that you will measure with the free chlorine residual daily test.

A normal pool comparator chlorine tests typically show total chlorine only. Since clean chlorinated water contains no combined chlorine, total chlorine in a sanitized pool is the same as free chlorine. They won’t differentiate from each other. But without a separate measurement of free chlorine, it is impossible to confirm the absence of combined chlorine.

For this reason, it is important to monitor both total chlorine and free chlorine. You can then subtract the free chlorine measurement from total chlorine to confirm the level of combined chlorine (total chlorine – free Chlorine = combined chlorine).

The best Total Chlorine residual is 0.0 but once it starts to rise by 0.2 ppm then it’s a good indication that there is a problem starting to develop with sanitation-combined chlorine picking up-free chlorine is sliding down and you need to get busy and that’s what this article is about!


Free Chlorine vs Total Chlorine


Your swimming pool’s water-free chlorine level should be in the range of 1 – 4 ppm, and pH between 7.2 – 7.8. The “combined chlorine” level is not measured directly but is calculated by subtracting the measured free chlorine level from the Total amount of Chlorine.

All forms of chlorine produce hypochlorous acid (HOCL) and hypochlorite ion (OCL-) when added to your swimming pool water. The hypochlorous acid and hypochlorite ion, together, are compounds called Free chlorine (FC). Hypochlorous acid is 60 to 100 times more effective than hypochlorite ion at killing or oxidizing microorganisms.

Hypochlorous acid is the active killing form of chlorine in water. Hypochlorite ion is secondary to Hypochlorous acid a reserve defense or a weaker form of chlorine. When you test for free chlorine, it does not distinguish between hypochlorous acid (HOCL) and hypochlorite ion (OCL-)

After the initial kill Chlorine will start to combine with other chemicals that are in your pool.  This combined chlorine is tested as the Total Chlorine residual. It is really important that you are able to keep a strong residual in your pool every day as contaminants are introduced every day that residual should be Free of Chlorine.  


What is the difference between Free Chlorine and Total Chlorine

Free chlorine involves the amount of chlorine that’s available to sanitize contaminants while total chlorine is the sum of free chlorine & combined chlorine which is a weaker type of disinfectant directly bound with the contaminants. …………………………read more


How Do I Raise the Free Chlorine In My Pool


If you are looking to raise the free chlorine residual once you differentiate between combined and free chlorine residual that is occurring in your swimming pool there are a few things you can do along with the simplest solution of adding more chlorine to your pool water. You can see this when you Testing Pool Water.

If total chlorine and free chlorine are equal, the chlorine has not started reacting. As long as the chlorine is effectively attacking pollutants, the free chlorine value will start to decrease, making the total chlorine slightly higher. When the difference exceeds 0.2 ppm, it means that the combined chlorine in the pool is climbing very high and needs to be reduced. But How?

To eliminate combined chlorine, it takes a surge of chlorine, to overcome the load. The general rule of thumb in the pool business is a shock of 10x your combined chlorine level in additional free chlorine.

  • Adjust alkalinity
  • Adjust pH
  • Most test kits measure free and total chlorine, so you subtract: Total Chlorine – Free Chlorine = Combined Chlorine
  • Calculate the proper amount of chlorine needed for Breakpoint Chlorination
  • Watch this video to learn about Breakpoint Chlorination


What is Combined Chlorine

Adding Chlorine to your swimming pool should not be as complicated as pool stores make it out to be with some basic understanding you can be “the Master of your pool” Stay here for expert articles like this at MyWaterEarth&Sky-when you add Chlorine to your pool water it forms hypochlorous acid. How effective it works as a disinfectant is dictated and influenced by the other chemicals that exist in ………………………………………………………. Continue reading





Reducing chloramines or combined chlorine will raise the production of free chlorine. Indicated by a strong chlorine smell. Irritated eyes, skin, and breathing problems are experienced by swimmers. Breakpoint chlorination is the point where chlorine levels exceed the total chlorine demand, and the pool water begins to build a residual of free available chlorine (FAC). Theoretically, exceeding the “breakpoint” prevents increased levels of chlorine byproducts like chloramines.


How do you lower Combined Chlorine?

When you measure the water in your swimming pool, the amount of combined chlorine in the water should be less than 0.5 PPM. If the numbers are higher, the pool may need to be shocked to get rid of the odor that comes with high amounts ……………… more



JimGalloway Author/Editor


References: Science Direct-Hypochlorous Acid



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