Question about the water pump pick up tube going into the fresh water tank on a 2018 328M. Does anyone know where this goes into the tank, how long the tube is, is it flex pipe or some other sort of tubing?

Is there or what is the minimum amount of water that is expected to be able to be picked up, especially since the main tank and auxiliary equalize.

I put in 30 gallons, measured with a flow meter, but I am sucking air somewhere. No visible leaks but my lines have lots of air in them and I can see the air going through the pump strainer.

I am suspecting the pick up because if I completely fill the tanks I dont have this issue. I am unsure at this time at what level it stops sucking air.

I have a call in to GD, and I am continuing to investigate myself as I have time but thought I would see if anyone else has experienced this issue or know anything about the pick up tube?

Thanks!
Floyd