Two weeks ago, I noticed that my above ground pool cover on my 21 foot round pool appears to be sinking in the middle. Today I noticed that the cover is so tight at this point that it is about to rip. I am assuming I must have a leak in the pool. I cant look inside the pool without removing the cover however, based on where the center of the cover sits, it looks like there is about 2 feet of water that remains. I am concerned that when it snows or rains, either the cover will rip or perhaps the walls will collapse. What should I do? Should I remove the cover for the winter? Its too cold to add water and I certainly cant go inside the pool at this point to look for a leak. Please help.