(06/13/2006) - This product is superior. I did an experiement comparing it to a generic carbon. This is the Abstract: ABSTRACT: This is a review of two carbon types, a generic carbon and Two Little Fishes, Hydrocarbon. Each carbon type (unused) was tested for its ability to absorb an organic blue dye and to what degree, if any, that it leaches phosphate. The Hydrocarbon absorbed organic dye in 90 seconds and leached zero phosphate. A used sample of Hydrocarbon (1 month old in Phosban reactor) was “almost exhausted” and leached zero phosphate. The generic carbon absorbed organic dye in 150 seconds and leached 10ppm phosphate. A used sample of generic carbon was not available and not tested. To review the whole experiment go here: http://reefcentral.com/forums/showthread.php?s=&postid=7549901#post7549901