You may not even need to close the tank valve, just close some/all things downstream of it to create some backpressure. If you listen close you should hear a click when it activates, and then another click when it re-opens.
I'm trying to find some porn filmed by a dog wearing a GoPro. - SharonaZamboni
Hunter, when you get bored, will you put a taco in my elephant's hands for me? - Hat