Evaporation and chlorine loss


Well-known member
May 25, 2007
Recent weather here has been hotter during the day and colder at night than pool temps, leading to pretty good evaporation. I was wondering if evaporation itself has any affect on chlorine loss.

It's generally recommended that when one shocks to make sure the FC level holds overnight. If evaporation causes chlorine loss, this could cause one to think they are losing something to organics and need to keep shocking when they really probably aren't.


TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
No, evaporation does not cause chlorine loss. However, higher temperatures do increase the rate at which chlorine is lost. And wind can increase aeration which can somewhat increase chlorine loss. So some of the same factors that increase evaporation also increase chlorine loss.