I finally re-did my pool this automn and recently closed it. I brought the water level down 4 inches under the returns and tried to blow the air with my shop vac.
However, after draining and disconnecting filter/pump, I noticed that the water was still draining. Initally I thought it was because my filter/pump are lower than the pool, but it was weird because my hoses where coming from above pool water levels. When I closed the valves and than reopened, it stopped, so I guess it was a vaccum effect.
The question : what do I need to do to make sure nothing freezes and bursts?! It seems like there's always some water in the bottom of the skimmer, which I don't understand. The drain and skimmer now have a hose each joining at pump, so I would figure that closing the drain hose would allow to empty skimmer hose, but I don't think it's working like that. What am I missing? Just don't want to beak my new pool! Also, the new returns have an external thread, so my old plugs won't work. Do they make new external thread plugs that won't get caught in the ice and prevent breakage when the ice moves up and down?