On March 24th my FC was 6.5 and my CC showed just a tinge of pink (0.0 to 0.5 range) and CYA = 30
This was my first hint of CC since I started taking care of my pool so I immediately went into shock mode and added a gallon of 10%.
The next day I measured FC = 15.5 (definitely in shock mode).
Today (16 days later) my FC has only come down to 12.
I have a solar cover on, so I suppose loss to sunlight is minimized, but I expected there would be more demand.