I have an automatic pool cover. When I close the pool for the winter, How far below the skimmer do I drain the water level? Since the cover rest on the water, if I drain below the return eyeballs, this will make the cover sag and could damage it? I have plugs for the return eyeballs, but will it be a problem if the water level is above the return eyeballs but below the skimmer? I read somewhere water level is supposed to be 3"-4" below skimmer with a auto cover.