I happened to be developing some film today, and I noted that the small white "gear" with three "blades" can be adjusted so that the expert tanks will rotate in one direction, or in two directions ( that is, will reverse after after a certain traverse ). Naturally I began to wonder when one would use one way rotation, and when one might use the back and forth rotation. I have been using the back and forth rotation with my expert tanks, but I am careful never to overload the tanks with too much solution....thus, I develop only a few sheets of film at one time. Can anyone speak to when "one way rotation" should be used? I did note that with the one way rotation the speed of the drum is not as easily adjusted, i.e., the rotation appears to be very much faster then I recall, and setting the speed dial does appear to have much affect.