I've read the sticky on closing an inground pool and have been getting all the supplies together while waiting for the water temperature to drop below 60. The recommended order is to get the pool balanced, raise FC to shock level, add polyquat, and then DRAIN. I have a pretty big 53K gallon pool with a main drain and valves that allow me to operate my pump and circulate the water in the pool even if the water level is below the level of the skimmers. The valves can be turned to draw water only from the main drain, so the water level can be lowered anywhere.
It seems like such a waste of chemicals to shock 53K gallons of water and add polyquat only to drain 15-20K gallons of it a day or two later. I've also wondered about the impact of dumping water with Shock-level FC and polyquat into the environment. Given the size of this pool and the amount of chemicals it will require to get the FC to Shock level (poolmath estimate is 11 gals of 12.5% liquid chlorine and ~3 quarts of polyquat), doesn't it make sense to DRAIN the water first, then raise FC to shock level and add polyquat?
I figure it will be hard to determine the number of gallons left in the pool after draining so poolmath won't be as useful, but I can use the TF-100 to determine my FC levels. Any thoughts?