Looks pretty good, except I would add a baffle where the water overflows from the fuge and from the main inlet to help control bubbles. Also, with a return compartment that small an autotop-off is pretty much a must. What is that feeding the fuge?, If its a uv I'd say ok, if its a media chamber, like phosban or de-nitrate, or a skimmer I wouldnt feed it with that. And where's the skimmer going?
And out of curiousity who would that be in ur avatar?
I'm sure reefer714 will chime in with his recommendations, master of all sumps fuges and the like