I'm going to ask some very general questions. What's the deal with agitation during development? I've always done the 5 seconds every 30 seconds thing, but now I'm reading that in some cases people recommend 5 sec/minute, etc. Obviously, it must depend on developer and film, but is there a standard to follow and experiment with? What are the effects of under or over agitation? By the way, I shoot 35mm and 120 and develop in a Patterson tank (the black plastic one) I've had for years. Does the tank make a difference?