Artsy cube , DIY, with the higher back sump, hiding powerheads on wavemaker and Tunze nano skimmer. Glass (or plastic?) piece in the center, to which the sps frags are glued sideways. Quite original approach, I was impressed.
ukguy:
Agu posted somewhere at forum DIY bottle skimmer, air driven.
From not DIY, ready made: I used Rio nano skimmer ($30) on my 6g Nano-cube, needs only a little cut off of the plastic rim, to accommodate the intake tube. This skimmer is a little louder, than I would like it to be, but works well.