thank you watermom;
Here's my update:
Shocked the pool to 25; 12 hours later my beautiful water is back.
I have no plans/desire to drain and replace water to correct high CYA problem, so my questions are these:
1)Using bens best guess chart, if my cya levels remain above 100, Is it correct that as long as I keep my FC between 8-15 I should experience no difference in my water than i would if the numbers were "normal"? By normal I mean; cya 30-50 with a fc between 3-6.
2) Is there any legitimate health concerns with maintaining these higher levels of chlorine, or is it really no different because of the actual effectiveness/release points of the chemicals?