Does metal sequestrant eat up some of the chlorine? I've been losing 5-6 ppm of Chlorine daily and I usually only lose 3-4. I did an overnight test and I lost .5 ppm. I did a drop test and it remained clear.
Water temp does influence CYA loss, but not so sure that would explain your situation. A CYA of 40 would seem to be adequate based on your conditions.Will having the water temperature around 84-86 also cause bigger drop in chlorine?
Hummm, I don't know about that one.could Iron (iron bacteria) be coming from the pine trees behind the pool?
I confirmed Iron by lifting the stain with Vitamin C test.Hey, sorry for missing the previous mention. Unfortunately I don't have a whole lot I can add to this. I can say that neither iron nor iron bacteria would be introduced to the pool from pine needles. There's nothing special about iron bacteria, it would die quickly but even if it were to it doesn't synthesize iron so if it were carrying iron in to the water it wouldn't carry any more or any less by dying faster or slower.
The metal sequesterant may well be causing a higher FC demand, but that seems a bit higher than I'd expect. If you don't think you have iron in your water supply, what are you adding the sequesterant for? Are you getting staining that you've confirmed is iron? That seems unlikely given a vinyl liner, but if there's a stain that is being lifted by a vitamin C test then it's possible.
Then that leaves us with a big question - where did the iron come from?I confirmed Iron by lifting the stain with Vitamin C test.