What media does everyone use in there emperor 400s? I'm thinkin of picking up some media for my three emp 400's media cartridges to increase the filtration properties as much as possible, I was also thinking of possibly filling them with pollyfill? Anyways whats everyone using and what are the better choices for this application? I was thinking bio-media of some kind would be best? But what fits good and works great? Any and all help much obliged!