With a DSB in the display,I'd go with a LR rubble fuge,I'd grow microalgae on the rubble for the pods to graze on and chaeto in suspension.A small powerhead in the fuge might be a good idea to keep the chaeto moving about.As for LR,I've never been a fan of the 2lb per gal rule,especially with a DSB in that size tank(lot of surface area).I think an open aquascape with 1lb per gallon would do the trick.I'd also add 2 additional water outputs to bring the total up to 5(2-seios,1 return,and an additional 2)