Black Tank flush with valve closed

wopachop wrote:
Is it common for people to close the valve with the hose still running in order to prime the tank with some fresh water?

The guy running my PDI told me to do this - said have your wife look down the toilet while your running the flush. She came around the corner and said tell me what? I said to him, go ahead - you tell her.

I keep my valve open while flushing - have a clear elbow connected to monitor the water color.