Very informative and makes sense, Chem_Geek. I didn't realize that the addition of the bleach would raise the pH and and assumed that I was OK to initiate the closing process at 7.6 without further adjustmemt. I falsely assumed that the polyquat was the culprit for the spike. And yes, your assumption of a CYA of 50 and jump of FC from 5.0 to 13.0 was right on.

All of this being said, how do you guys recommend that I proceed with the remaining step of covering the pool? Based on Chem_Geeks explanation I believe I understand that the pH would drop back down as the FC falls from the shock level. But will it continue to drop significantly and quickly enough once I add the light-blocking cover? If this were your pool, would you feel comfortable covering it up for the winter with FC of 13 and (based on CG's calculations) a current pH of 8.2? Or should I leave it uncovered for an additional day or two?

Jim