I have a 5x15 air pillow for my 25x15 oval pool - this will be the third year I've closed and I have still yet to master keeping that thing centered in the pool. It has two grommets on it, one on each end in opposite corners. I center it up and tie it off to the ends of the pool. I can't make it too tight because I don't want the rope to hold the winter cover up but I always leave it tight enough it shouldn't move. EVERY YEAR first bit of wind or rain the thing shifts to one side of the pool .. I can't keep it in place no matter what I do. Does anyone have any suggestions? I thought about filling gallon jugs with water, tying off to them like anchors and dropping them straight down but I have a feeling rain water will just push the cushion and drag them across the pool floor. Any ideas? Rope with stakes to the outside? Help!