I would just fill it up with live rock rubble.
PErsonally Id remove the black box.... cos its a bloody eye sore lol.
IF you wanna refugium, just get a little 12"x18" tank, with a small pump, and grow pods in a seperate tank.
musho said:chaeto would do more than live rock rubble, if you can give it light put in macro algae.
I can forsee is getting light and good water flow around it in that black box.
And dude, you can never have enough tanks
musho said:Chaeto is a macro algae, it eats nutrients like nitrates and phosphates and also provides a safe haven for lots of pods.