http://www.youtube.com/watch?v=wMGZ0GWDXEY
This video (courtesy of LssTV) shows a Reef Octopus Biopellet Reactor which is outfitted with a propeller in the base of the unit to aid in reaching a perfect tumbling pattern for the pellets.  Initially the goal of the new pellet-specific reactors was to make sure the media did not clump and allow for hydrogen sulfide to accumulate, which could effectively poison the tank.  Taking a look at this design though, you can see that the reactor really does a good job of getting every bit of the media a fairly equal amount of exposure to the incoming water.  Previous systems allowed for some media to stay in certain areas which meant that some pellets were more used than others.  Because the pellets actually break down as they are spun makes this case somewhat irrelevant, but what about GFO/Phosban or activated carbon?  It seems like a great way to ensure you get the most out of every batch of media you run in your tank.  If you do go this route, remember that the flow rate in the video is not our recommendation, please follow the manufacturer’s instructions.  If you are running GFO in a reactor, be sure you don’t bubble it too much as it will break down into dust and end up in the main tank.  Finally, there is no established recommendation for tumbling your activated carbon, although we’ve seen more and more people running carbon in actively moving patterns.