I have a pool and spa close together. When the filter is on, the spa water flows over a slight "waterfall" ( a few inches tall) and into the pool. That's how the water is circulated. I want to cover the pool with a solar blanket, but I am concerned about the part where the water flows down from spa into pool. If I cover the pool, the water will fall on top of the blanket, most likely weighing it down and sinking it. Any ideas? Thank you!