The MR1 wasn't specifically designed for biopellets but you can use it if you make plastic discs with holes in them. You can't use the foam that comes with the MR1. I think most people buy the plastic mesh used for cross-stitching at a craft store and then they cut circles out of it. The SMR1 was designed for biopellets and it is what I use.
I run mine off a manifold with a gate valve so I don't use a pump but I have seen people using MJ1200 or Mag 3 pumps. Be sure to have some sort of valve so you can adjust the flow. The main issue I had with it was how the pellets were tumbling. With only 500ml in there they weren't tumbling well at all. I sent an email to NextReef and they suggested adding more media to create more back pressure. Now that I have 750-1000ml in it they seems to be tumbling fine.