Clarification on overnight Free Chlorine test

[PaulinSoFla]

Couple quick questions on Doing the SLAM protocol & overnight free chlorine test. The SLAM says to leave my pump running 24/7, I have a spillover spa so wont the aeration of the waterfall reduce my chlorine levels? do I leave the pump running overnight when doing the OCLT for this reason or should I switch my valves around so to not create a spillover? Also if my morning test is an hour or so after sunrise but no direct sun on pool will this make a difference? I ask because my pool started off pretty clear & has been crystal clear without any cloudiness whatsoever for the entire day but free cl still dropped from 21.5 @ 9pm to 14.5 @ 7:am, both tests read cc at 0.5

other #'s
calcium hardness 550
total alkalinity 90
CYA 55

Thanks again.

 

[mknauss]

The spillover will not cause FC loss.
As long as sun is not on the pool surface, there is little UV effect.
With that FC loss, you have organics somewhere. Your signature shows you use test strips. I assume you now have a proper test kit. Please modify your signature.