Remember that you don't *need* to drill. You can buy/make overflows that use a siphon to transfer water over the lip of the aquarium. They usually have two siphon tubes running in tandem, so that you don't wind up with a flood if one loses the siphon. Not as reliable as a drilled hole and more complicated, but a less-scary option to get started, at least with a tank or two.thanks again guys!!!! I really appreciate the simplicity of these set-ups (once they are set up!!) and will certainly integrate both the shunt/head tank and the open return line as, hydraulically, they make a whole hell of a lot of sense. Still daunted by getting holes into all the tanks, but one step at a time. I guess I will have to be shuffling fish around this summer and doing one or two at a time.
Cheers, Jase