My PB method to close pool is as follows: Lower water 6-8 inches below skimmers...blow out skimmers and waterfall lines....add antifreeze to those lines. Make sure all valves are left open at the equipment pad. I am concerned about not doing anything with the return lines...he says as long as the valves are open that I have nothing to worry about. Anyone see any problems with this method? Thanks. I live in Southern Michigan.