I purchased the solar rings about a week ago. Instead of buying a pool heater, I figured I would try them out and save a couple of thousands of $$$. In just 4 days with the rings in the pool I got my water temperature up from 75 to 84. I only lose about 1-2 degrees at night, compared to 5-7 before the rings. My neighbours pool without a solar cover or rings is 6 degrees cooler than mine. Great product and well worth the money.