I plan on closing my IG over the weekend. I live in Central Illinois and my water temp is around 65 degrees. I am concerned with my lines freezing. My skimmer and my main drain come to a T before going into my pump. Each has a shut-off valve. I have 2 return lines that T off underground. What is the best way to blow the lines? In what order? Should I be concerned about my Main Drain line because I can't see how you could keep water from not freezing in it? Please help

Joe