Chlorine is widely used as a disinfectant in swimming pools and drinking water to kill harmful bacteria and viruses. However, it is important to understand the difference between free chlorine and total chlorine to ensure the safety and cleanliness of the water.
In this article, we will explore the definitions of free chlorine and total chlorine, their significance, and how they affect water quality.
What is Free Chlorine?
Free chlorine refers to the chlorine that is available to actively disinfect the water. It exists in three forms: hypochlorous acid (HOCl), hypochlorite ion (OCl-), and chlorine gas (Cl2). These forms work together to kill bacteria, viruses, and other microorganisms in the water.
Free chlorine is responsible for maintaining the residual disinfectant level in the water, ensuring that it remains safe for use.
What is Total Chlorine?
Total chlorine, on the other hand, refers to the sum of both free chlorine and combined chlorine. Combined chlorine is formed when free chlorine reacts with ammonia and organic compounds present in the water. This reaction produces chloramines, which are less effective in disinfecting the water compared to free chlorine. Chloramines can cause eye and skin irritation and give off a strong chlorine odor.
Why is Free Chlorine Important?
Free chlorine is crucial for maintaining water quality and preventing the spread of waterborne diseases. It acts as a powerful disinfectant, killing harmful microorganisms that can cause illnesses such as diarrhea, skin infections, and respiratory problems. Free chlorine also helps to control algae growth and remove organic matter from the water, keeping it clear and safe for swimming or drinking.
The Role of Total Chlorine
While free chlorine is the active disinfectant, total chlorine provides a measure of the overall chlorine content in the water. By monitoring total chlorine levels, pool operators and water treatment facilities can ensure that there is an adequate amount of free chlorine available for disinfection. If the total chlorine level is significantly higher than the free chlorine level, it indicates the presence of chloramines and suggests the need for additional chlorine treatment.
Maintaining the Proper Balance
To maintain a safe and healthy swimming pool or drinking water, it is essential to maintain the proper balance between free chlorine and total chlorine. The ideal ratio of free chlorine to total chlorine is typically around 0.6 to 0.8. This ensures that there is enough free chlorine available for disinfection while minimizing the formation of chloramines. Testing and Treatment Regular testing of chlorine levels is crucial to ensure that the water is properly disinfected. Test kits are available to measure both free chlorine and total chlorine levels. If the free chlorine level is too low, it indicates a lack of disinfection, and additional chlorine should be added. If the total chlorine level is significantly higher than the free chlorine level, it suggests the presence of chloramines, and shock treatment or super chlorination may be necessary to break down the chloramines and restore the proper balance.
Understanding the difference between free chlorine and total chlorine is essential for maintaining safe and clean swimming pools and drinking water. Free chlorine acts as an active disinfectant, killing harmful microorganisms, while total chlorine provides a measure of the overall chlorine content. By monitoring and maintaining the proper balance between free chlorine and total chlorine, we can ensure that the water remains safe for use and free from waterborne diseases. Regular testing and appropriate treatment are key to achieving and maintaining this balance, providing peace of mind for swimmers and consumers alike.
The author of this post is Mathieu Robert, certified from La Cité Collégiale in construction and building techniques.