I have a 26' round on-ground pool which is 3 years old. the solar cover that came with it finally fell apart at the end of last season so I am now in search of a new one. The local pool store here where I purchased my pool (New Brunswick, Canada) only carries one kind which is I believe is 8 mil blue/black cover with a life expectancy of 3 years. When I search online there are many options from thickness, longevity, color and shape of bubble - any ideas as to which is best band for my buck. Also is there a preferred site that offers good prices including shipping.