I finally got to try out my counterflow chiller. It's a standard 3/8" copper tube with the garden hose around it. A friend and I brewed a 5G batch of Belgian Wit, and it cooled the hot wort down to 70 F as fast as it would flow out of the bucket. I had to turn down the water or it came out closer to 55 F.
This sure beats the ice water bath I used to use. Can't wait to try it on AG this summer!