I'm starting to lower my opinion towards this supposed need for massive biofiltration units. Truth is, if you need that much surface area dedicated to such colonies, your tank is ridiculously overstocked. Not to mention if your tank is highly planted, the bacteria are taking away too much of the plants' preferred nitrogen source - ammonia.
I think that the "normal" amount of bacterial colonization surface area found in proper filtration and on the tank surfaces is more than sufficient for what is needed to keep a very healthy system. Would you believe me if I told you that my betta bowls are "cycled" just because they each have one small rock that I never remove? Just for fun I test them from time to time before doing water changes and the ammonia is always 0 as is nitrite. And the small amount of nitrate present makes it obvious that there is an active biofilter - living on one little rock. Really shows how little all of this insanely overdone biofiltration is needed.