I have installed the winter cover. Its just a typical "tarp" style cover and I used to air balloons to help prop it up in the middle. I have researched other threads on here about covering vs. not covering, and the various types of covers. I bought this style, so I am sticking with it until it breaks/gets holes. After reading the other posts, I guess there is a guarantee that I will have to pump water off of the cover? I guess I had this idea in my brain that it could be stretched taught enough so that there were no dips...but in reality I am finding that is not possible. A couple pics of the cover attached. I still have to put more water bags on.