I have an all inclusive cube, not the same, but similar enough. Take the bioballs out. Put LR back there. Take a filter pad out, put LR and chaeto in there - refugium. Put LR in the third chamber under the other filter pad. I added a chiller, metal halides, and two ph in the tank for added flow. I am now looking into skimmers and auto top off systems. As for the fish jumping in the back. The only thing i can say is maybe a nylon mesh screen or eggcrate.Or, what I would consider the most effective (so light still gets in the back) Take 3 pieces of plexi and glue them flat to eachother, but make the center one an inch or too higher so the outside pieces can overlap the back wall of the tank between the tank itself and the filter chambers. You know, that little divider wall that makes it so hard to stick your arm all the way to the bottom of your filter chamber. You can make it as high as you want so fish dont make the leap, but rebound back into the tank. Hope this helps.