If you haven't drilled the tank yet I would go with two smaller bulkheads for the overflow and set it up as a Herbie (google it if you don't know what that is), I have a 75 gallon tank with a single 1.5 inch bulkhead in the overflow and had a hell of a time getting it to be quiet. It sounded like a running toilet all the time. Finally had to devise a weird pseudo Herbie type attachment on the single bulkhead.
Oh, and welcome to Canreef
