I picked up a used Waterbox Reef 70.2 that had the filter compartment removed (baffle taken out) in order to accommodate a filter floss roller. I don't want to jump on the roller bandwagon because (to me) it's a hassle to replace the rolls compared to the plastic filter cups that I regularly fill with floss in my current tank. I want to rebuild a compartment to house a filter but I'm not sure how to close it off so the water is forced to flow through it before entering the rest of the sump. I'm thinking I could use a small (8"x8") plexiglass box set on top of a bio brick and cut a hole on one side near the bottom for water to flow out. I'm also thinking I could just stuff the box with floss; do I really need a filter cup or sock?