The Oase 600 Biomaster comes with carbon prefilterfoam for its first stage of filtering. Look like black foam. I read this will reduce my ferts (I am have a new planted aquarium and am fertilizing, adding trace, and iron on the Seachem schedule). Also using CO2. I have also read this is a misconception and it won't impact my ferts. Very confusing when there is conflicting info. Does anyone have experience with this? Thanks guys.