What is Chlorine Demand
It is the difference between the amounts of chlorine applied to amount of free, combine or total available chlorine remaining at the end of contact period (specified) which should be at least 30min.
Chlorine Demand is a pool water chemistry topic that is getting more attention due to changing climates, consumer's water chemistry and understanding of the problem. It is also becoming a greater issue in many private & commercial pools.
Chlorine demand = chlorine dosage - chlorine residual