I have a 125 african cichlid tank. Currently, I'm running an FX5 and two Aquaclear 110s, and I've gotten sick of dealing with the FX5. I have a few extra tanks lying around, and am thinking about putting a sump on the 125, for better filtration and (hopefully) more flow. The tank is currently running and also up against the wall. Does this mean that drilling it is out of the question? Should I get a HOB overflow? Pros/cons of sumps and HOB overflows?