Oh! The pains of my heart! Those two videos I linked to are of these things. In the 40 meg one at about 1:50-2:00, I think, he shows a shot of the front of the tank when it fires. The water level drops about 2-3" inches I think.
I have a feeling that you can't push the water seal in the vent pipe any higher than water level of the tank the surge chamber is in. Since they're both open to the atmosphere the pressure holding them in will be the same. That said, I only drew the vent to an outside catch basin because that's how it was described, and I think that's what I saw in a video.
People who name their tanks and have sequels to them are silly.
So it's a sudden negative pressure? Hardly seems like it would produce much flow at all compared to a regular surge device. The polyps on his coral went one way, then the other, then stopped. I would want that thing firing every ten seconds.