I have a south facing roof, in the Atlanta, GA area, that gets about half the sun during the day due to tree shade. With this half of the available sun for the day, will it be effective? My pool gets some shade, so it doesn't get quite warm enough, I'd like to raise and keep the temp. about 5 degrees or a little more, 13.5k gallon above ground pool. I thought about a natural gas heater, like 100k btu, but no one has ever given me even a ball park est. of what it would cost to raise and keep the temp. 5 degrees with it!! But, if I can keep the temp. that 5 degrees with solar, then that's the way to go. Now, if I do that, from where the pool is, is actually three stories high. How does the water get up there? Do I need a seperate pump? If so, how does that work? Would the pump be regulated by the water temp, or does it just run water through it constantly? Thanks.