Marc, those dimensions come up with it being 600g(599g actually)quote] no it is 718 if you do lengh x with x hight(in inches) divided by 231 you get gallons. aslo as far as a sump i think you do want 1/3 the tank size( about 240gallon sump); also make sure the pump that it pumping back to the tank is stronger then the one pumping in to the sump. As far as bio media if you want somthing cheap and effecive(sp) i go with nylon pot scubby(sp). If you want somthing that is nicer looking i go with bio balls wich are not cheap. For that kind of setup you want about 3-5 turn over an hour(2,154-3,590). One more thing you will ned mech filtration at the beging of your sump try these
http://www.drsfostersmith.com/product/prod_display.cfm?c=3578+3579+16746&pcatid=16746. Also heres a link to a sump
http://www.monsterfishkeepers.com/forums/showthread.php?t=83107. hope this helps