Not pretty but functional.
Here I removed the filter box and cut out section 1 and 2 to make larger fuge.
LR rubble will go into the bottom 4" or so and chaeto into the remainder upper part. I closed the bottom inflow up so the water would only surface skim into the filter box. Added a piece of black plastic to the box to keep light spill over from fuge lighht more contained. The 3 holes were already there and serve no purpose. Also closed up some of the overflow so more of the top surface would skim.
After reinstalling the filter box I scraped away the back glass paint so I could silicone a small reflector with a 6500k screw-in 10wt fluorescent. This way I can run it 24/7 without light spill-over into the tank.
Added an old Odyssea 24wt PC light. The ballast is actually a long tube, I guess an electronic ballast without the box, that fit perfectly under the existing Biocube's reflector. I cut the fan slots off of the back reflector to get more air flow.
I am going to use a Maijet 1200 for return. Gave it a leak test and ran it a bit and works great. Might have to add stronger fans or one in the back somewhere if it runs too hot. I want the 1200 for stronger flow though 900 would be cooler running.
Will be my zoo only tank.
Will post more as I fill, add sand and rock. Thanks for looking.