Mike, when I had my 135g that was un-drilled, I had problems with the overflow, especially when I was out of town working. Twice while I lived in Lampasas and working in Nacogdoches, the overflow failed...wife screaming at me on the phone...me trying to tell her what to unplug... a 5.5 hr drive home and back to make it in time for work...etc..I then put red tape on every plug she needed to unplug. When I returned to working in town, I drained the tank and drilled it...I WILL NEVER HAVE AN UN-DRILLED TANK AGAIN...