Back in 2006 I ran just over 700 feet of 3/4" hose to my pond when we had a bad drought. My pond is small (about 1/3 acre), and a few feet below my well. I ran the well nonstop for about 3 months and was only able to add about 3 feet of water during that time. As you noted, the fish liked to congregate in the cool water just below the hose. I had the hose suspended about 2 feet over the water to add some aeration, and I think that also attracted the fish.
If I have to do it again, I'm going to bury some thin walled pipe. The hose just adds too much friction to be effective.
