But if I'm correct in my understanding of the flow direction, in other words, with that constant flow of water in from the moat, and the idea that there may have been a hinged door at the entrance at some point, (which I've read about), that maybe they had control of shutting off the flow. So if the flow was in that direction, they could shut it off, set up the 'hydro jack', open the flow and push the plugs. And during this time, interrupting the flow of the system to do this effective breaks the bubble in the lower chamber and shuts off the system.
I never meant that the 'production' of water from the system was what filled the system, (if that's what your implying).
Am I misunderstanding the system flow?