My 155 is drilled in the back, 2 overflows what a racket. So I built 2 Hofer Gurgle Busters and that solve the problem. No I can hear if the sump is low and top it up right away.
This is my thread on it and a link to the Hofer build page:
http://www.canreef.com/vbulletin/showthread.php?t=58944
http://home.everestkc.net/jrobertson...struction.html