I just had my pool closed and they didn't blow out the skimmer lines or main drain. They just poured 1-gallon of antifreeze down each suction line at the pump. Then they placed a 1-gallon jug (1/2 full of antifreeze) in each skimmer. This is the same method as last year and it worked. The antifreeze was (-50 for RVs). As for the returns, they blew each one out and screwed a cap into the return to seal off the water. Note that I have frost free skimmers.
20 x 44.5 single roman end, ~33,000 gallons, 10 feet deep, garrett vinyl liner, Hayward SwimClear Cartridge Filter, Hayward 2 HP Pump, Cirrcupool RJ60 SWG, Hayward 140k BTU Heater, Polaris 380 with Booster Pump
20 x 44.5 single roman end, ~33,000 gallons, 10 feet deep, garrett vinyl liner, Hayward SwimClear Cartridge Filter, Hayward 2 HP Pump, Cirrcupool RJ60 SWG, Hayward 140k BTU Heater, Polaris 380 with Booster Pump