I have a 125 gallon 6 foot tank I purchased used that is housing african cichlids at the moment. I have a eshoppes HOB overflow that goes to a small sump on the tank (20 gal). I've learned a lot since I built that setup years ago, and I'm curious if anyone has run into a tank this size that didn't have a tempered bottom. I assume I'll have to drill the back on this so I can properly plumb it. How do people normally build their overflow boxes when they drill the back? Is it best to just buy an overflow?