Free Chlorine, Combined Chlorine, Total Chlorine

Chlorine is a crucial element in pool maintenance, but understanding its different forms is essential. Three main types exist: free chlorine, combined chlorine, and chloramines
Three main types exist: free chlorine (FAC), combined chlorine (CC) and Total Chlorine (TC). Chlorine is a crucial element in pool maintenance, but understanding its different forms is essential. Each plays a unique role in pool sanitation and affects water quality differently. It is essential we understand the differences.

Free Chlorine:

Free chlorine refers to the active chlorine available in the water, responsible for killing bacteria, viruses, and algae. It sanitizes the pool and ensures it remains safe for swimmers. Maintaining adequate free chlorine levels is crucial for optimal pool health.

Combined Chlorine:

Combined chlorine forms when free chlorine combines with contaminants like sweat, urine, and body oils. It’s less effective in sanitization and can cause irritation. Differentiating between FC and CC is vital, as excess combined chlorine indicates the need for shock treatment to eliminate contaminants.

Total Chlorine:

Total chlorine is the sum of both free chlorine and combined chlorine in the pool water. It represents the overall chlorine present, including the active sanitizing form (free chlorine) and the combined chlorine, which is essentially chlorine that has already reacted with contaminants in the water. Maintaining an appropriate total chlorine level is crucial for ensuring effective pool sanitation. It indicates the overall chlorine reserve available for disinfection purposes. However, simply relying on total chlorine levels alone can be misleading without understanding the ratio between free and combined chlorine.


Chloramines, the byproducts of chlorine reacting with organic matter, contribute to the infamous “chlorine smell” and can irritate swimmers’ skin and eyes. Regular shocking, adequate ventilation, and maintaining proper chlorine levels can help control chloramine formation. Chloramines can be dramatically affected by Cyanuric Acid levels. To high of CYA will make it very hard for chloramines to burn off raising CC and TC but not FAC. For more info please about how CYA affects chloramines please click here:

Effects in a Swimming Pool:

Insufficient chlorine levels can lead to poor water quality, resulting in cloudy water and increased risk of infections. Excess chloramines can cause unpleasant odors and discomfort for swimmers. Regular testing of both TC and FAC levels helps pool owners understand the state of their water and take appropriate actions, such as shock treatment if CC levels are elevated. By managing TC effectively and maintaining the right balance between FC and CC, pool managers can ensure a healthy and enjoyable swimming environment for users.