I have a kidney shaped pool with a spa. The spa is elevated and creates a waterfall with the pump. I was looking at solar covers and wanted to get thoughts on this. Should I get a large rectangle and cut to size to go on top of the water or get an oversized solar cover that would go over both the pool and spa. I have seen that solar covers are supposed to be on the water, so I’m not sure if doing this would lead to more heat loss or if it would be negligible.