More surface area = more space for bacteria to grow, but the amount of bacteria that grows is dependent upon ammonia levels (bioload). I mean, just because you add more space, doesn't mean bacteria levels will double. The bacteria still has to eat, and more space isn't going to help that -- you would have to have an increase in bioload, as well. Now, if you were going to do this in order to add more fish, I think it would work -- more bacteria could grow, and they would have enough to eat, because bioload would be greater.