i just purchased a 100 gallon acrylic tank which has a built in overflow & sump in the back of the tank kinda like a biocube.... the sump has 3 sections the first where the water overflows into a chamber which fills up & overflows onto a drip tray which then trickles down bio balls under a wall to the last chamber were the return pump is.....now heres my question ... should i keep the bio balls & carbon bags or should i replace that section with live rock, sand, & macro algea? wich would filter the tank better its a FOWLR? i plan on using a backpack skimmer seems tho theres no room in sump for one? any advice would be great ...also if i go with LR + algea should i put a light back there also?? thanks TRT!