Seems like the Aqua Clear brands are pretty popular with lots of Nano owners......as they have a nice large filter chamber to make into a refugium.....I use a piece of fine foam (30 micron filtering size) which is used to polish the water, and let the actual filtering process get handled by the liverock and sand......I sometimes hang a bag of activated charcoal or most recently have been using Purigen in a mesh bag hung in the pump inlet chamber......works great.