Best bio pellet reactor?

[Reef Pilot]

I have the Vertex UF20 reactor. Works great for me. It is narrow and tall, so uses a small footprint in my sump. I run it off a T from my return pump, and control the amount of tumble with the valve that it comes with on the input side. Just be sure to use mesh (from Michaels) inside, instead of the sponge filters or get the Vertex Pro-Bio Peller kit. The output is near the input to my skimmer.

I use the Vertex bio pellets along with MB7 with mine. I ramped it up slowly, but managed to run the whole 1000ml bag in the reactor. Then I just top it up about every 3 months, to keep it tumbling all the way to the top for maximum efficiency.