My fresh tank has emptied itself overnight. I added a shut off, but one time I forgot to reopen it and the fresh tank had sucked in on itself a bit because of no ventilation. I opened the valve and quite a bit of pressure was released. No damage done, but lesson learned. I have recently added extra tubing to the overflow and created a loop higher than the fresh tank. This was suggested by someone on the Georgetown part of this forum. Will try it out tomorrow, probably the simplest solution if it works.
2015 Georgetown 329DS
2014 Chevy Equinox