After having two CO2 tanks mysteriously go empty over the course of months, I finally sprayed everything down with Star San. Previously, I had checked all of the connections for leaks. However, this time I found the leak in the form of a microscopic hole in the middle of one of the manifold t-fittings. I can't see the hole with my eyes, but it slowly bubbles up when doused with Star San. So remember, kids, always check EVERYTHING for leaks.