Secondary determinants in FC lost to sunlight

[ValleySooner]

I'm curious what factors impact the amount of free chlorine that's lost to sunlight. Obviously, CYA levels and available sunlight (UVA/UVB radiation?) are primary determinants. However, given any fixed amount of CYA and sunlight, will your free chlorine lost to sunlight be a function of total free chlorine available? Or is it a function of the surface area of the pool? Or volume of the pool? Or all of the above?

For my CYA level (50), my target FC is from 4-8. I'm wondering whether I'll lose more FC each day if I run my pool at the top of the spectrum as opposed to the bottom.

 

[JasonLion]

FC lost is a percentage of the starting FC level, so the higher your starting FC level the more FC you lose to sunlight.

You need to keep FC at the minimum level regarless, so you often have to raise the FC level towards the top of the range each evening just to make sure it is still at the minimum the next evening (unless you add chlorine more than once a day).