Jim,
I don't use mine but once in a great while. I have a switch on the dash overhead but added one by the pump so while I'm at the pump I can turn it on and off without going back inside the bus.
You don't want to run it dry, so what I do is hook up the drain hose and then open the discharge valve and then open the inlet valve and then turn it on and let it run until I hear a pitch change in the pump, then turn it off. Then I open the gray tank valve and let grey water fill my Y fitting, then open the black tank and let the grey partially fill the black. Then repeat the above process until the black is drained and rinsed. Do this until the gray is empty.
I have been thinking of going to a 1 inch discharge hose to use at campgrounds instead of the 3 inch gravity hose. I have seen some of the newer rv's that have gone this way but haven't heard much on how it's working out.