Drill your Tank no prob, 4 easy steps
#1 Get a glass bit 1 1/2" approx depending on your bulkhead i use 1"int, it standard for 100gls and the price is 80$ canadian pick it up at home depot or any glass shop.
#2 u need a square template of where you want your hole, I use a 4"x4" piece of plywood 1/4" thick with a standard hole saw(what u use to cut holes for doornobs out) same size as your glass bit, buy one at home depot, find the center of the template and drill it out presto theres your template.
#3 Turn the tank upside down make sure you have a cup of water.Place your template in the corner tape in place.
#4 Get your Diamond bit ,and cut away pouring water on it often to keep it cool. very important do not add too much presure when you reach the end or glass will chip.
Thats it.
RobinL
P.S i would incorporate a Durso overflow for the noise.just a suggestion.