Herbie is the best thing going right now
I keep linking to Richards build thread because it does an awesome job of showing how it is plumbed
http://canreef.com/vbulletin/showthr...ghlight=herbie
Here is the reef central link that created this style
http://www.reefcentral.com/forums/sh...hreadid=344892 lots of reading if you are up to it.
Basic concept though is the tank is drilled with three holes on the bottom of the tank in the overflow. Two holes for 1-1/2 pipe, one is the primary drain that is throttled with a ball/gate to eliminate and splashing, gurgles bubbles etc, the second is an emergency drain line just in case the primary is blocked for any reason. The the third hole is for the 1" return line. Take a look at Richards pics they show really well how it is plumbed.
You are more than welcome to swing by my place to see how I have mine hooked up if you are interested