I've got a Sapphire Aquatics BC29R in my 29gal Biocube which has been running for about 3 weeks. I'm not sure if it will fit in your nano, but I know they have different custom skimmers for different tanks. I get about half a cup of cloudy tea-coloured skim a week, but my bio load is light. Its not loud either.
http://www.sapphireaquatics.com/onlinestore/
FYI- Canada Customs totally raped my shipment! You should've seen the box. Even the Postal guy was like "damn". Broke a piece but nothing crazy glue couldn't fix.... And then they charged me $5 for the inspection....