Thanks for the advice Peggy. It will be vented, properly and legally installed. It's a quick solution to meet tankage requirements in order to move into a live-aboard marina. Hopefully it will see little use otherwise a larger main tank will be installed. From past experience bladder tanks usually fail because of poor installation, abrasion or fittings leaking at the tank. I just didn't want another one of those "I wish I would of..." moments somewhere down the road.