Whatever you do, don't do like I did when I ordered holes to the size of the pipe instead of the bulkhead for my mechanical filtration. I had to quickly scramble and order the larger sized holes that would accomodate the bulkheads. A lot of tanks have two returns. On my big tank, each overflow box has two 1.5" drains and four 1" returns. But it's a really big tank, and each overflow box is 4 feetMaybe I will just use my current sump then, I spent enough on the tank I don’t want to spend much more right now. I’ll ask one more question, I’m doing a single end peninsula overflow I think they normally do 2x (1”) drains and 1x (3/4) return but I can choose my hole size. Should I go bigger?