I use Stress Coat to dechlorinate my water both in my work tank (5gal FW) and home tank (15Hgal BW). The bottle says that it takes the chlorine out "instantly", but I always stir it for 1- 2 minutes before adding it into the tank. I usually change 1 gal out of the 5 gal at a time, and 5 gal out of the 15 gal at a time.
I haven't had any fish die that I know of as a direct result of a water change like this, but I was wondering if anyone else had a definitive time of how long it takes to remove the chlorine?