Frags 120 gallon reef room divider (LOTS of pics added April 8, 10)

[xtreme]

I would go with a herbie overflow, as JDigital said you will require two holes for that. 1.5" bulkheads should do the trick.

[Fragzilla]

whats a herbie?

[JDigital]

This is a basic Herbie Overflow system.

One Drain takes the ALL the flow for the tank... the 2nd pipe is above the waterline in the overflow box. Should the main drain get blocked, the water level with rise, once is rises over the emergency, that pipe will be able to handle all the flow as it is straight through without any valves..