The one I just got also came with some kind of chemical filtration packet as well, but I'm a big fan of seachem purigen so I used that in its place.
Also added more bio media from the Fluval 404 POS that this filter replaced. I figured it was an advantage using established biomedia and so far so good. No Ammonia or Nitrites yet. If i have to fault fluval on anything it was not providing enough bio media.