Hi MFK, I have two used bio filter up for sale. Below are links about the two filters. $400 each OBO
http://www.aquaultraviolet.com/products/filters/ultima2/2000
http://www.wlimstore.com/filtration/biowavefilter.php
http://www.aquaultraviolet.com/products/filters/ultima2/2000
http://www.wlimstore.com/filtration/biowavefilter.php