i don't like it because: it does do a hell of a job absorbing odors, chemicals, and other things; but for that reason (highly absorptive) it reaches it max potential rather quickly (obviously some quicker than others based on many a factor) then it begins to leach back into the system. It can also leach phosphates which promote algae growth. I just stick to regular water changes and plenty of bio media/filtration and don't seem to have any problems. But on the other hand i do know a lot of people run carbon, so to each his own