Pool Chlorine: FAC, TAC, and CAC


All pool water has a chlorine demand. Almost everything that enters the pool uses up chlorine. The chlorine demand is increased by pH, environment, temperature, and swimmer contamination. The amount of chlorine that remains after the demand is met is known as the chlorine residual. The goal is to always maintain a chlorine residual.


When testing your pool for chlorine, there are three types to consider.


  • Free Available Chlorine (FAC)

FAC is the actively available disinfectant in the water that sanitizes and kills pathogens after the chlorine demand is met. FAC is the type of chlorine we want in the water at all times as it kills the contaminant very quickly, helping to maintain healthier pool water.


  • Total Available Chlorine (TAC)

TAC is the total of all chlorine compounds in the water and is the less active available disinfectant in the water.


  • Combined Available Chlorine (CAC)

CAC is an adverse product that forms when free chlorine (FAC) reacts with two possible types of contaminants in the water – chloramines. These are compounds that leave the distinct smell of chlorine and can irritate a swimmer’s eyes and skin. CAC is a weak sanitizer, around 40 to 60 times less effective than FAC.


Reach breakpoint which is the level of sanitizer that needs to be added where the chloramines change the chemical structure and either gas off into the atmosphere or get filtered out. This process, super chlorination, is giving chlorine the boost it needs to kill algae, reduce odors, and maintain a residual sanitizer level in the water. After breakpoint chlorination is reached this means that the nasty smell goes away and all that remains is FAC.


Swimming pool maintenance isn’t a burden you must undertake by yourself. At Sparkling Clear Pool Service, we understand what it takes to keep a pool clean, sanitary, and well-maintained. Be sure to contact us at 214-361-0255 for all of your pool maintenance needs in McKinney, Allen, Frisco, and beyond!