Coralife 300g Cone Skimmer
It's got a brand new pump in it from Coralife, as well as new air adjustment/tube/sponge. Rated for 300gal tank, so I'd guage 150-200g or smaller with high bioload.
I inherited it last year with a 90g tank and it's just way to efficient for my low bioload coral based tanks so I have to only run it periodically.
Currently running in my SPS frag tank, but it's just more than I need anywhere. It needs a decent sized sump for it's footprint -
14-1/2"L x 9-3/4"W x 26"H
Can see a video of it running here: