Did you ever end up flipping the check valve when you said your midship bags wouldn’t drain or prune up all the way? Is the “loop”necessary by the midship bags or can I just run my midship vent tube lines and T directly to the rear bags? I’m about to install my midship vents and just trying to make sure it fills, drains and vents correctly using the check valves. There is no markings on the check valves for which direction is the path of flow.