The instructions tell you to allow the cover to touch the water surface. However if you drop the water level, like I do, that doesn’t work well with a pool pillow I purchased. I’ve had to dip water off the cover and reposition due to the weight of rainwater collecting. I re-stretched the cover and pitched it so water runs off better. If you live in an area that has a lot of rain, be aware of the weight of collected water. It will pull this cover into the pool. I caught it right before the cover fell in. The winch doesn’t tighten well. However the construction of this cover is of excellent quality. Very thick and durable.