So my biggest tank I am running now is a 55 gal acrylic. Attached are the pictures of a 5ft 90gal acrylic I am buying from my buddy at work but can figure out why the bulkheads are placed dead center in the bottom of the tank or why you would need 6 holes? He got it from someone off offer up that never had it set up and my buddy never had it set up. I am thinking it was for a sump set up? Please take a look and give me some ideas. I have never done a sump and not sure I would want to. My 55 is some what overstocked so i am running 2 large sponge filters, and large hob bio wheel and a fluval 406. Thank you all for any advice. Can I just plug the hole or what kind of setup should I do? I still have to build a stand and canopy for it so it will not be up and going for a while.