i am in the planning process of building a large acrylic island style tank with center overflow, tank will be 8'x4'x30", i haven't decided if i will do sand or bare bottom. eventually i would love to keep 1-2 blue spot rays in the tank as well as move my 5 tangs from my 230 waterbox. i know i will do a large sump, but am wondering about drains and return pumps. i currently run A cor 20 on my waterbox and have been happy with it, i would like to utilize 2-3 1.5" drains and either run 2 cor 20's or go with 2 external pumps like the isaki or reeflo style. the return pipe plumbing will come up through the center overflow with 6-8 lineloc style return nozzles in various locations on the overflow, and possibly a couple of return pipes located through out the display for extra circulation. any thoughts or input on the return side of things would helpful.