:bounce: Typically the returns are just run through bulkheads placed in the back walls.
Few people run any returns through the side walls also as I do unless the tank is a build in. My sidewalls are painted black just like my back walls. I have six 1" return bulk heads on my back wall, and two 1" return bulk heads on each side wall. I also have four 2" bulkheads in the back wall. Two feeding a glass-holes overflow box flowing to a sump/refugium with skimmers, and one each feeding a Sequence Dart in a closed loop and a Sequence Snapper in a closed loop. They are fed thru custom slotted inlet boxes made by glass-holes. :^: