Looking to make a solar heater this summer. Not sure what the feed back here is for those. Really just going to coil 100' of irrigation line and let the sun do its work. Hoping only for a few degrees, but the more the better. Was thinking of using a solar powered fountain pump. That way, it only runs when it's sunny. Thoughts or suggestions? What would be a good flow rate? 100gph? More or less? Should have about 5-6 hours of hot direct sun each day.