Helping a friend today (watching his business while he went to the doctor) and he turned on the pump in his pond when I arrived to get the ice off the pond. The pump is at the bottom of the pond and pushes water to the surface (I did take a temp reading on the water shooting up and it was 39º compared to 32º on the surface). It took about 2-3 hours to clear the ice on about half the pond.
When enough water was open I decided to try my 2wt rod I keep in the truck.
Only took one cast (and a long wait for the fly to get deep) to get a 'gill's attention.