How do you treat Chlorine Demand?

Chlorine demand treatment time and difficulty could vary

Keep timing in mind when you are treating a demand…it’s important. Checking the chlorine residual a few hours after treatment could show the presence of free chlorine, and one might assume the demand is broken and no further product application is needed. However, if slow-reacting contaminants are present in the water, the chlorine can be used up as they continue to react. As a result, the chlorine residual will end up at zero as more time passes which means that the demand is not truly broken. This is why it is very important to add the entire amount of recommended product as instructed, continue to test frequently, and be sure the free chlorine residual holds at 1-4ppm for a full 24 to 36 hours.

Unfortunately, there is no easy cure for many chlorine demand situations. In most cases, there are still only two options. The first is to apply the appropriate amount of chlorinating product (usually determined through testing) and the second is to replace some of the water with fresh water that has no chlorine demand. In situations where the chlorine demand is accompanied by very cloudy water, a floc treatment may reduce the demand by physically removing some of the contaminants from the water. Keep in mind that a floc treatment or water replacement does not actually cure the demand but only lessens it. It will be necessary to re-test and apply the newly recommended amount of chlorinating product.