When you purchase a swimming pool of any size or any type inground or above ground you will learn that chlorine normally is the main chemical that will keep your pool clean, clear, and sanitized free of contaminates but there are different types of chlorine you need to know about that are discussed here. 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. The equation is (Combined chlorine + Free chlorine = Total chlorine)
Having been an inground pool owner myself for many years I have found that keeping things simple is the best way of controlling your swimming pool or else you’ll be running up to the pool center panicked that you won’t have your pool opened by Memorial Day. Understanding this article hopefully will take some of that anxiety away.
Introduction:
Chlorine plays a vital role in maintaining the cleanliness and safety of pool water, serving as the primary disinfectant to combat harmful bacteria, viruses, and algae. However, understanding the different forms of chlorine present in pool water is essential for effective water treatment and maintenance. In this guide, we delve into the nuances of free chlorine, combined chlorine, and total chlorine in both traditional chlorinated pools and saltwater pools. By exploring these distinctions, pool owners and maintenance professionals can gain valuable insights into optimizing water quality, ensuring a healthy swimming environment, and minimizing potential risks associated with inadequate chlorination. Let’s dive into the world of chlorine and its critical role in pool sanitation.
Free chlorine and total chlorine are key parameters monitored in water treatment to ensure safe drinking water. Free chlorine refers to the amount of chlorine available for disinfection purposes, primarily comprising hypochlorous acid and hypochlorite ions.
In contrast, total chlorine represents the sum of both free chlorine and combined chlorine, which includes chloramines formed when free chlorine reacts with organic matter. While free chlorine acts as the primary disinfectant, effectively eliminating bacteria, viruses, and algae, total chlorine provides a measure of the overall chlorine concentration in water. Understanding the differences between these two parameters is vital for maintaining optimal water quality and ensuring the effectiveness of disinfection processes.
Free chlorine refers to the amount of chlorine that is readily available to kill any bacteria or other contaminants, as soon as they appear in the water. The optimal levels of free chlorine are between 2 and 4 ppm. Free Chlorine is the best chlorine and needs to be monitored and closely tested daily.
Combined chlorine is a term used to describe free chlorine that has bound itself to a contaminant or organic material, such as skin oil, sweat, or urine. While it is acceptable to have combined chlorine levels below 0.5 ppm, a clean and disinfected pool will have no combined chlorine present.
Having too much-combined chlorine can result in a strong chlorine odor, eye redness, and skin irritation. Total chlorine is the sum of free and combined chlorine. It is easy to monitor the total chlorine levels, but this measurement is only useful if there is no combined chlorine present.
First things first, to make sure that your pool is clean, disinfected, and safe, it is essential to routinely monitor and maintain the chlorine levels. You can test your pool’s chlorine levels by using test strips, test kits, or an electronic chlorine tester. Test strips are the easiest to use.
Here’s a table summarizing the main differences between free chlorine and total chlorine:
| Feature | Free Chlorine | Total Chlorine |
|---|---|---|
| Definition | Chlorine available for disinfection purposes | The sum of both free chlorine and combined chlorine |
| Composition | Comprises hypochlorous acid and hypochlorite ions | Includes free chlorine and combined chlorine (chloramines) |
| Purpose | Primary disinfectant in water treatment | Measure of overall chlorine concentration in water |
| Measurement | Directly measured using test kits or sensors | Calculated by subtracting free chlorine from total chlorine |
| Effectiveness | Kills bacteria, viruses, and algae effectively | Less effective disinfectant due to the presence of chloramines |
| Presence in Water | Present immediately after chlorination | Formed after free chlorine reacts with organic matter |
Understanding the distinction between free chlorine and total chlorine is crucial in water treatment and maintenance to ensure effective disinfection and safe water quality. If your pool is clean, the combined chlorine value can be assumed to be 0, so the total chlorine amount should be made up of just free chlorine. However, there is no sure way of knowing if your pool is completely clean, without testing the difference between free and combined chlorine levels, as contaminants, such as bacteria and other microorganisms are not visible to the human eye. The presence of algae or a characteristic lingering chlorine smell are both indicators of the excess of combined chlorine.
The 3 Types of Chlorine
Measuring the amount of chlorine in your pool is essential if you want to keep your pool water clean and sanitized. Maintaining the proper levels of chlorine in your pool will also allow the water to be clear and sparkling. While it’s recommended that you test your pool water every day, your pool should be fine if you only test. Testing the pool water is particularly important if your pool is left uncovered, which exposes it to sunlight, rain, leaves, and wind.
There are three methods that you can use to test for free, combined, and total chlorine in your pool, which include chlorine test strips, chlorine test kits, and an electronic/digital chlorine tester. Chlorine test strips are made from plastic with a chemical pad attached to a stick. The chemical pad can react with the water and will change color to provide you with a rough estimate of how much free chlorine, combined chlorine, and total chlorine are in your poo
3 types of chlorine exist in your swimming pool which include
- free chlorine
- combined chlorine
- total chlorine.
Free chlorine involves the amount of chlorine that’s able to sanitize contaminants in your pool, while
Combined chlorine refers to chlorine that has combined directly with the contaminants.
Total chlorine is the sum of free chlorine and combined chlorine. All important test parameters for determining the sanitizing productivity of your swimming pool.
Knowing where these tests are in comparison with each other can give you a better handle on the chemistry of pool water and how treatment will be successful or not.
Chlorine, a widely used disinfectant in water treatment, exists in three main forms: free chlorine, combined chlorine, and total chlorine. Free chlorine includes both hypochlorous acid (HOCl) and the hypochlorite ion (OCl-), which are responsible for disinfection.
It is the active form of chlorine that kills bacteria, viruses, and other harmful microorganisms in water. Combined chlorine, also known as chloramines, forms when free chlorine reacts with ammonia or organic compounds in the water.
Unlike free chlorine, chloramines are less effective as disinfectants and can produce undesirable tastes and odors. Total chlorine represents the sum of both free chlorine and combined chlorine and is crucial for assessing overall chlorine levels in water. Monitoring all three forms of chlorine is essential for maintaining adequate disinfection and ensuring the safety and quality of drinking water.
What is Free Chlorine in a Pool Water
3 types of chlorine exist in your swimming pool which include free chlorine, combined chlorine, and total chlorine. Free chlorine involves the amount of chlorine that’s able to sanitize contaminants in your pool, while combined chlorine refers to chlorine that has combined directly with the contaminants. Total chlorine is the sum of free chlorine and combined chlorine.
- Free chlorine is the amount of chlorine, measured in parts per million (ppm), that is available to eliminate harmful microbes and neutralize contaminants.
- Free Chlorine is not yet bound to microbes, contaminants, or chemicals in the pool water.
- Monitoring free chlorine is the most important part of swimming pool maintenance to avoid harmful contaminant levels and keep control of the pool.
You add chlorine product to pool water to sanitize it. Once in the water, free chlorine forms hypochlorous acid and hypochlorous acid, which are active disinfecting compounds that kill disease-causing microbes. This is what you are aiming for when you add chlorine to your pool water.
When chlorine bonds with these and other organic compounds, such as sunscreen or swimmers’ body fluids, chloramines are formed. Chloramines, also known as combined chlorine, leave the pool through off-gassing.
A buildup of chloramines causes the “chlorine smell” that swimmers in the water find irritating. This sour smell may be an indication of poor water quality. Regularly testing for free, combined, and total chlorine levels will help to prevent or reveal water quality issues before problems arise.
Free chlorine: ideal range 2.0 to 4.0 ppm, safe range 1.0 to 6.0 ppm. Once the Free Chlorine is used up as it starts to react or oxidize with contaminants like nitrogen & ammonia in the water it becomes Combined Chlorine a weaker version of Chlorine.
What Is Combined Chlorine in a Pool
Combined chlorine, often referred to as chloramines, is a byproduct formed when free chlorine in pool water reacts with organic compounds such as sweat, urine, oils, and other contaminants brought in by swimmers. These organic compounds combine with the free chlorine, reducing its effectiveness as a disinfectant.
Chloramines not only diminish the chlorine’s ability to kill harmful microorganisms but also contribute to the characteristic “chlorine smell” associated with pools. Additionally, chloramines can irritate the eyes, skin, and respiratory system of swimmers. To maintain water quality and ensure a comfortable swimming environment, it’s essential to monitor and control the levels of combined chlorine in the pool through proper water treatment and regular maintenance, including shocking the pool to break down chloramines and replenishing the free chlorine.
Combined chlorine develops when free chlorine binds to contaminants during sanitization. When combined chlorine is present in the pool water it indicates that contaminants are present which is pretty important information you need to analyze the health of your pool.
A good working sanitized pool contains zero combined chlorine. Maintaining the proper level of free chlorine in the pool water greatly reduces the likelihood of detecting measurable combined chlorine levels.
- Combined chlorine: ideally less than 0.2 ppm, safe below 0.5 ppm
What Is Total Chlorine in a Pool
Total chlorine in a pool is a critical parameter that encompasses both free chlorine and combined chlorine (chloramines). It provides a comprehensive measure of the overall chlorine concentration in the water. While free chlorine is the active form responsible for disinfection, combined chlorine consists of chloramines formed when free chlorine reacts with organic contaminants introduced into the pool by swimmers.
Monitoring total chlorine levels is essential for ensuring adequate disinfection and water quality maintenance. Ideally, the total chlorine level should closely match the free chlorine level, indicating minimal chloramine formation. Regular testing and proper maintenance procedures, such as shock treatments to break down chloramines, are necessary to keep total chlorine within the recommended range and provide a safe and enjoyable swimming experience.
Combined Chlorine is the portion of chlorine in the water that has reacted and combined with ammonia, such as nitrogen-containing contaminants, and other organics that come from a swimmer’s perspiration, urine …………………………..read more
Free Chlorine + Combined Chlorine = Total Chlorine
The sum of combined chlorine and free chlorine is total chlorine (combined chlorine + free chlorine = total chlorine). Inexpensive chlorine testing will only show the total chlorine. Since clean chlorinated water contains no combined chlorine, total chlorine in a sanitized pool is the same as free chlorine.
True chlorine is easy to test for in pool water when compared to free chlorine or combined chlorine, which is why many of the more inexpensive chlorine measurement tests will specifically test for total chlorine. In clean water, the amount of total chlorine can be used to determine the amount of free chlorine in the water since combined chlorine should be at 0 ppm.
The measurement of total chlorine residual is useless because the measurement doesn’t denote the different amounts of free chlorine and combined chlorine, it won’t be able to tell you much about how healthy your pool is.
Even though it can be more affordable to measure for total chlorine, it’s not nearly as effective, which is why you should heavily consider obtaining sensors or a test kit that measures both free chlorine and total chlorine.
However, without a separate measurement of free chlorine, it is impossible to confirm the absence of combined chlorine. For this reason, it is very important to monitor both total chlorine and free chlorine. You can then subtract the free chlorine measurement from the total chlorine to confirm the level of combined chlorine (total chlorine – free Chlorine = combined chlorine).
*Total chlorine: should be equal to free chlorine most of the time
*Total chlorine – Free Chlorine = Combined chlorine
*Combined chlorine + Free chlorine = Total chlorine
Free Combined and Total Chlorine Work the Same in a Saltwater Pool
In a saltwater pool, the principles of free chlorine, combined chlorine, and total chlorine work the same as in traditional chlorinated pools.
- Free chlorine: This is the active form of chlorine responsible for disinfection. In a saltwater pool, free chlorine is produced through the electrolysis of saltwater, where salt (sodium chloride) is converted into hypochlorous acid (HOCl) and hypochlorite ion (OCl-)—the effective sanitizing agents.
- Combined chlorine: Just like in traditional pools, combined chlorine in a saltwater pool refers to chloramines, which are formed when free chlorine combines with organic compounds. These chloramines are less effective as disinfectants and can cause irritation and odor.
- Total chlorine: Total chlorine in a saltwater pool is the sum of both free chlorine and combined chlorine. It represents the overall chlorine concentration in the pool water.
While the method of chlorine generation differs between traditional chlorinated pools and saltwater pools, the concepts of free, combined, and total chlorine and their roles in maintaining water quality and sanitation remain consistent. Regular testing and maintenance are necessary in both types of pools to ensure proper chlorination levels and a safe swimming environment.
- Stop Adding Chlorine. The simplest step to bring down chlorine levels is to stop adding chlorine to the pool. …
- Remove the Pool Cover. …
- Use Chemical Agents to Reduce Chlorine Levels. …
- Drain Some Water and Refill the Pool. …
- Keep Testing.
Conclusion:
Free chlorine vs total chlorine in a saltwater pool works the same as in a freshwater pool. It involves the amount of chlorine that’s able to sanitize contaminants, while combined chlorine refers to chlorine that has been combined directly with the contaminants. Total chlorine is basically the sum of free chlorine and combined 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.
The equation is (Combined chlorine + Free chlorine = Total chlorine)
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) …………………………………………………………………………read more
References:
MyWaterEarth&Sky What is Combined Chlorine
Feature Image Combined Chlorine by Poolonomics.com
FAQ’s
What is free chlorine in a pool, and why is it important? Free chlorine in a pool refers to the chlorine available for disinfection purposes, primarily comprising hypochlorous acid (HOCl) and hypochlorite ion (OCl-). It is crucial for killing bacteria, viruses, and algae, thereby maintaining water quality and ensuring a safe swimming environment.
What are combined chlorines, and how do they affect pool water? Combined chlorines, also known as chloramines, are formed when free chlorine reacts with organic compounds like sweat, urine, and oils brought into the pool by swimmers. Chloramines reduce the effectiveness of chlorine as a disinfectant, contribute to unpleasant odors, and can cause eye and skin irritation in swimmers.
How can I measure the chlorine levels in my pool? Chlorine levels in a pool can be measured using test kits or electronic sensors specifically designed for monitoring chlorine levels. These tests typically measure both free chlorine and total chlorine, allowing pool owners to assess the effectiveness of disinfection and overall chlorine concentration in the water.
What is the ideal range for chlorine levels in a pool? The ideal range for free chlorine in a pool is typically between 1.0 and 3.0 parts per million (ppm), while the total chlorine should be within 1.0 ppm of the free chlorine level. This ensures adequate disinfection without irritating swimmers.
How can I maintain proper chlorine levels in my pool? Proper chlorine levels can be maintained by regularly testing the water and adjusting the chlorine dosage as needed. This may involve adding chlorine-based sanitizers, shock treatments to remove chloramines, and ensuring proper filtration and circulation of pool water.
Are chlorine levels different in saltwater pools compared to traditional chlorinated pools? While the method of chlorine generation differs between saltwater pools and traditional chlorinated pools, the principles of free chlorine, combined chlorine, and total chlorine remain the same. In saltwater pools, chlorine is generated through the electrolysis of saltwater, producing free chlorine to sanitize the pool water.
How often should I test the chlorine levels in my pool? It is recommended to test the chlorine levels in a pool at least twice a week, especially during periods of heavy pool usage or hot weather when chlorine demand may increase. Additionally, testing should be done after heavy rainfall or when adding new water to the pool.
Can I use chlorine alternatives in my pool? While chlorine is the most commonly used disinfectant in pools due to its effectiveness, there are alternative sanitizers available, such as bromine and mineral-based systems. However, it’s essential to research and understand the specific requirements and limitations of these alternatives before using them in your pool.