Couldn't Drain Pool Cover?

[junkmail9999]

Sorry if this is all dumb, but this is my first time opening my new pool in the spring...I got it late last fall.

I have a solid pool cover, not mesh. My pool pillow did deflate during the winter, and the cover had quite a bit of water on it. I thought I might be able to fill my pool at the same time that I was draining the cover, by sliding a hose under the cover and draining the top at the same time with a pump. After quite a few hours, I noticed that the water level was not really changing. I know that this may have been a knucklehead thing to do, but I thought that solid pool covers were supposed to be drainable.

I then stopped filling the pool and decided to pump the pool cover off only, which seemed to be dropping the water level in the actual pool below where it was when I closed the pool, but not really getting any water off of the top of the cover...It kept about 8-12 inches of water on it the whole time. I finally came to the conclusion that the cover must have been leaking the whole time.

When I did finally dump the whole mess in the pool and take the cover off, I didn't notice any large holes, just some weaker spots here and there in the cover where some light could get through slightly. Any ideas of what actually was happening? It appears that I was draining the pool with the cover pump at the same time that I was filling it, as if it were a mesh cover. Shouldn't I be able to drain and fill at the same time, or at least get most of the water off of the cover? Would this happen if the cover was leaky (it was the cover's first season)? Could the deflated pool pillow have anything to do with it?