Recently set up a 12 gallon nano cube with a new bio filter that I produce. Check out the link below for photo's. http://www.redstoneinc.com/prod03.htm
It is PVC. Works great. I have been producing the stuff for years for Wastewater and colling tower plants. It has also been used at some of the larger ocean parks. Don't know why it has taken me so long to put it out for the personal aquariast. Check out my new picks.