I wanted to like it and knew going in that it would only add a few degrees of heat. I was not expecting the water flow to be reduced so much. We're using just one for our 12ft Intex pool, using a 1000 GPH pump and the flow rate is significantly stepped down. I'd estimate the flow output is only a third of its normal output when engaged. I think this is putting extra wear on the pump motor and keeping the pool from circulating the water as efficiently. It's hard to tell if it's actually doing anything, it might be adding a degree or two but nothing of note. Considering we got it on sale I'm not going to waste more of my time returning it. Maybe during mid-summer, it might work better. However, by that time we won't really need it.

Would have been great if it weren't so pricey and took up so much room as well as compatible with my pool plumbing

Junk!! Waste of money -I had to throw it away by the end of the season DO NOT BUY

one of them just doesn't work. need 3-4 of those to heat 18 ft pool

It lasted five days before it broke and shot a geyser of water in my yard losing over 3000 gallons of water and pool chemicals from the swimming pool. It busted at the small connection area and after reading reviews it seems to be a common problem.