I've begun testing chlorine daily for awhile, just trying to get to know the pool better. Current test info, FC 4 to 6, CC 0, TA was 90 lowered to 80, CH 240, CYA 50.
What seems weird, first when I was running the pool up to FC 8 it would take 2 days to go to FC 4. Fine, sort of high consumption but hey, it's hot and sunny. Then I started just going to FC 6.0 and in a day it was down to 4 or 4.5. Most of the time my pH is at 7.7 or 7.8 or even 7.9.
Since TA has been creeping up with water additions I lowered it rather aggressively from 7.9-ish to 7.0 ish then aerated. So, today the pH is 7.3 and what seems weird is that I see no chlorine consumption at all, or nearly so. I raised FC to 6 (or maybe 6.5 tops assuming some measurement error while pouring bleach) and this evening FC tests at 6.0.
I always assumed that the suggested range for pH of 7.5 to 7.8 had to do with eye comfort while swimming, as well as scaling issues. But, does pH have any effect on chlorine loss?