CYA 90 (I know it's an issue; will drain 50% at end of season)
Water is clear, but I have accumulations of green algae(?) in the same places every day even after shocking and vacuuming.
Had FC at 24 for three days and just upped it to 33 yesterday. No appreciable drop in chlorine level overnight, but the green
stuff keeps on showing up. (see attached photos)
The crescent shaped ring seems to be right at the shadow line of the south & west walls.
BTW, pool calculator and the CYA/chlorine chart have different values from each other for shock level. Which one is best to follow?