Quote Originally Posted by chem geek
The answer to your question is a function of both CYA and FC (total free chlorine) levels since twice the chlorine level loses about twice the amount of chlorine per day.
If this is the case, then perhaps we should all be reporting the percentage drop in PPM that we experience each day, rather than the PPM itself?

I wouldn't have thought it was quite that linear - certainly chlorine loss after shocking seems much faster (even in percentage terms) than regular chlorine loss.