10-4 on the ball valves to isolate the darkroom plumbing----thank you. My plan is to use flexible washing machine hose from the hot and cold supply with shut-off valves as shown. I'll probably go ahead with the regulated mix, I certainly like the idea. I hope to get going on building the sink on my 4 day holiday weekend. My only concern about these plumbing plans is that I will have the drainage properly vented, I'm going to rely on the plumber for that.