How is combined chlorine calculated?

Combined chlorine is calculated using the difference between total chlorine and free chlorine. Total chlorine represents the sum of both free chlorine, which is available to sanitize the water, and combined chlorine, which is the chlorine that has already reacted with contaminants and is less effective at sanitation.

By subtracting free chlorine from total chlorine, you effectively isolate the amount of chlorine that is combined and no longer available for disinfection. This calculation is essential for pool operators as it helps determine the effectiveness of the chlorine levels in the pool water and whether additional treatment is needed to break down the combined chlorine, ensuring that the water remains safe and clean for swimmers. Running this calculation regularly can help in maintaining the appropriate chemical balance in the pool.