I've had this heater for 3 years and it does increase the temp of the water. The down fall is if it's a cloudy summer than it doesn't do as much. It requires a location that has no shade, and can catch the sun morning until evening. Overall a good purchase. *Side note, the two back legs did both break off and there was no rough handling just set up and take down each year, I just use some wood blocks to prop it up now. The leg structure could use some improvements.