If it is acrylic then it makes life very easy. I have two tanks that I drilled after they were set up. If its glass then I would have Eric drill it. I wouldn't do it while set up though. If its acrylic I would be happy to show you how to drill it and explain the plumbing.
Otherwise use a good quality overflow box. I saw one in doc fosters yesterday that used a lift pump to prevent trapped air from breaking the siphon.
Be forwarned however that overflow boxes are notorious for causing floods. I would dare say that a good majority of the members here have had the same bad experiences that I have with these devices. Just my 2cents.
One of the tanks is a 12g eclipse with a 5.5g sump/refug.
Edited by Holdencraft 33