I put in a new deicer for the koi pond. It's a 300 watt model in the shape of a rock. (I got it from Foster and Smith Aquatics, who were running a sale. They had great service, too.) When our old flat one stopped working, I put in the 1250 watt one for a while, but I was afraid it would use too much power over the long run. With the ice and rain storms we've had it also warmed up enought to melt all the ice. The fish like to line up like this for some reason.