how do you make a closed loop system?

[fishmonkey]

okay so I want to make a closed loop system WITHOUT DRILLING HOLES. My goal in my aquarium adventure is to minimize equipment in my tank for aesthetic reasons, and so that I dont have a bunch of stuff in the tank taking up space for the fish and stuff. So Im wondering, how do you make this closed loop thing. I think I sort of get the concept: it is a circular system. The water comes out of the tank, goes into a pump, and then is pumped right back into the tank. But how do I do it? By my understanding, all I need is a powerhead and some tubing right? I kinda want to be able to place it underneath the tank in the stand to keep it out of the way. Is that all I need?