I purchased a house with an IG fiberglass pool with an automatic pool cover, so this is my first season closing it. The previous owner always lowered the water level to below the skimmer, but not below the returns as that would be too low for the cover an overstress it and the tracks.
The problem with lowering the water level is that the cover will hold several thousands of gallons of water, and in my experience, whenever there's water on the cover, it raises the level inside the pool an equal amount, at least around the edges. Therefore, if the water doesn't get pumped off, the water on the cover will fill to the top of the pool, and then run off, while the water inside the pool will fill all the way to the top as well.
The problem is that I will be AZ for 3 months this winter, and won't be able to put a pump on the cover to pump it off. It may or may not be needed in Jan and Feb, but I'm sure it will in Mar before I get back. Rather than have to worry about it, I'm wondering if it would be reasonable to winterize with the water level way high? I can blow and plug the returns, use a Gizmo in the skimmer, us an empty bleach bottle jammed in the skimmer opening to raise the skimmer flapper and protect it, and jam extra foam inside the skimmer to provide additional freeze protection for the skimmer.
Given that I expect the water level in the pool to come up to the top edge anyway in the winter with rain and melting snow, it seems like it would be a good idea to instead raise the water level way up to start with. This way the cover will hold much less water and it won't be as critical to pump it off whenever the snow melts, etc.
Another consideration is that the pool is about 2-1/2" - 3" out of level, end to end. The lowest point is on the shallow end where the returns are, and if the water runs off the cover (or overflows the pool) here it will just run off the concrete into the gravel landscaping. This means that the water level at the skimmer end is always several inches below the other end of the pool, and it can't fill up completely at this end. This is another reason for not being able to lower the water level below the returns, as they are considerably deeper than they probably should be, and lowering the water this far would really strain the cover, particularly at the deep end.
I don't know how thick the ice will get on top of the pool, but that depends on how cold it gets, and my assumption is that probably 6" - 12" if it's like a pond or lake. It would seem to be better for the return plugs to have them well below the surface of the water, and this way they might not freeze into the ice, which would seem to be better than having them just below the surface.
What are your thoughts? Does this make sense, or should I lower the water like most people do when winterizing?