Re: leaving hookah set up
I've let a vase of water run from one bowl to the next if I'm smoking within a short time of the initial bowl but overnight, hmmm, ya know, bacteria grows really, really fast in a warm, wet environment where adequate substenance is available to it. That available sustenance is generally some form of sugar. Most shishas have molasses, honey, or glycerin in them, all sugars, which run or leech into the water. Overnight I'd say you would have a veritable smorgasbord for bacteria to grow. As you draw smoke through the water, it can pick up bacteria, transferring it directly into your lungs, another warm, moist environment . . . pneumonia isn't a fun thing to go through and it would seem to me that you would be setting urself up for a ripe case of it, or some other type of pneumonal infection. I'd take the few mintues to, at least, rinse and dry the vase and components of my hookah for overnight storage. Smoke happy.
Al Fakher Large Solid and a bowl of DM . . . life is good!