Do you know what a great use for all those bleach/chlorine jugs from the summer is? Keep about 10 to 15 of them...Then when you close your pool, you fill them about half way with water, and then use about three feet of clothesline rope to tie to the bottle and then tie to one grommet in the middle of each section of your AGP(above ground pool)then put the bottle on the cover...Not hanging from the side of the pool...That acts as a balast to keep the cover down. Early this past fall and winter, we had almost no rain or snow until after Christmas...so rather than filling it with water, the water jugs did the job...
However, to be safe, I always put an inch or two of water on the surface of the cover. But the jugs are ice, because as the wind blows from one side the water has a tendancy to get pushed to the other side, then you do have a cover that flaps a lot...But with the water jugs it doesn't. Before I started doing this, my cover would always blow off in heavy storms...Not any more
Air pillows will deflate if you over fill them with air...1/2 filled with air will be good enough, because as you get water and snow on the cover, it pushes down on the pillow...If it is full already the pressure is too much and it blows out from inside. It is like displacement. If you fill a bath tub to the top and then get in...what happens...You have a wet floor. Same with the water pillow...
Just my experiences fighting long midwest winters and winter storms.