It's not all good in the neighborhood tonight. Connected the water changes pumps for the freshwater. No leaks, okay, great! Plugged a pump in for a test run. Works great! Awesome! Unplug the pump.... the water's not stopping. Awe man, it created a full siphon. Had to close the ball valve to get it to stop.
I'm thinking I have to add a vent stack, but the ceiling is lower than the max head height of the pump. Vacuum breakers are brass, so that wont work.... probably have to lower the pumps so I can add the vent stack.