2013 Z1. Rear Sacs filling by themselves while docked and shut off?

[HoopsMT]

This is actually a problem I wish I had sometimes. Unfortunately, not now! The rear sacs on our 2013 Z1 fill to about 6"s when left with the power off. After draining ballast, I can hear the water pouring back into the hard tank, then into the bag from there. Fills as fast as when the pumps are on! Haha. Any idea what would cause this suction (assuming)? Maybe the vent line is plugged? thoughts?

Thanks!

[chpthril]

Need to rework the fill plumbing so the Y fitting that splits the fill to the tank and sac, is higher then it is now. Tanks are actually below the water line, so with that Y low, water can run right in to the tank.

[HoopsMT]

chpthil.....you're like on speed dial! The Y fitting we under the sac, pulled it up the side of the sac and it's all good. No more rushing water! The Y fitting was always under the sacs before, so I'm not sure why it just started behaving that way. Of course, I needed to say that cause I feel like an idiot. So for all the other mentally impaired, this threads for you!

Thanks chpthil! I love simple fixes!