Quick Definition:

Chlorine demand is the estimate of chlorine required to meet the consumption demand of microorganisms that consume chlorine.

What does Chlorine Demand for pools mean?

Chlorine demand is the amount of chlorine required that reacts with organic and inorganic contaminates in swimming pool water. Chlorine ends up being used when microorganisms consume chlorine and other inorganic materials and contaminates are oxidized by the chlorine.

Not having enough chlorine to meet the chlorine demand can result in cloudy, uninviting pool water. If this is the case, the typical remedy is to shock or superchlorinate the pool.  Shocking the pool results in a chlorine level much higher than the chlorine demand, overwhelming any microorganisms and completely oxidizing any other contaminates.


  • “Pool & Spa Water Chemistry, A Testing and Treatment Guide, Waterproof Edition, 2005. Taylor”

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