You stated above you got it from BRS????????Got it from LFS so it was cured for sure. As far as the HOB filter I have a Marineland Penguin 350 and it uses two cartridges with carbon preinstalled. I change them out every 3 weeks or so. I have a Octopus Skimmer coming in on delivery this monday. I'll have to empty 50% of my tank and move it out from the wall in order to install it because as of now, the skimmer won't fit with only 3" of space between the tank and wall.