My favourite are the vertex biopellets simply for the fact that they are readily available. That is, just about every LFS has them. They are a nice shape and size and tumble well. Having said that, I have never really had much of a problem with any of the biopellets on the market. I've tried mostly all of them now I think. In fact, my current reactor has some of the original biopellets (lentil looking pellets) as well as BRS biopellets, Vertex Biopellets and one other brand I forget. They are all tumbling together nicely. I actually like to buy up other people's discarded biopellets when they decided that they don't want to use them anymore
