My indoor pool will be one year old at the end of this month (specs in signature). For the past 8 months, the free chlorine demand has been pretty stable, with overnight FC loss of about 0.2 ppm, and a few bather-hours per week. Keeping the IC40 at 4% (with the pump running 24/7 in conjunction with the dehumidifier) had been keeping the FC level stable at 1.5-2.0 ppm ... until a couple of weeks ago when the FC level increased from 1.5 to 2.5 ppm over one week with the IC40 setting unchanged at 4%. The only change I made around that time was to decrease the pool temperature from 88 degrees to 86 degrees. Everything else remained unchanged, with the same few bather-hours per week, with environmental factors also unchanged in the indoor environment.
Could the functioning of my SWG be increasing/malfunctioning (producing more FC at the same 4% setting), or could the decrease in the pool temperature by only 2 degrees have such an effect on decreasing FC demand?
Pool water clear
CYA 15 approx. based on prior Tri-Chlor use