I'll be getting a 19cf pony botle for Christmas. I have an older Sherwood Magnum II with the dry bleed system. I would like to use this reg with the pony. My question is: Do I have to keep the bottle turned on all the time during the dive or can I just charge the line and then turn off the valve on the bottle, opening it only if I need it? I'm thinking with the dry bleed system, the valve has to be open during the entire dive to keep water out of the 1st stage.