Thanks for all of your replies, and I realize my question is not so easily answered because I too have been using Eheim's bio non-pro for many years 10+ and have had no problems but I guess what I'm really asking is has anyone done any informal testing btwn the diff. media and come up with a conclusion stating that A brand is better than B? The price btwn the 2 is very significant in my opinion and that's the primary reason for the input.