<a href=showthread.php?s=&postid=6362885#post6362885 target=_blank>Originally posted</a> by mope54
you have to level the tank...you could use self-leveling epoxy instead of shims.
also, if it were my house and I was putting a tank in the middle of the room (or anywhere not being a load-bearing wall), I'd crawl under the house and add support beneath the tank.