The Biochurns seem to be sized for anyone from the hobbyist to something like 40,000 gallons, I saw a video of one and a person is briefly in the shot next to it and is the same size as the reactor just about.
BR 150T is Just over 4 feet tall and rated at 40,000 gallons.
http://coralvue.com/biochurn-biopellet-reactors/
I was looking around for a new reactor because Im tired of how my Two Little Fishes 550 always is clumped up and I dont feel like I go through as much media as I should because its not tumbling. I have been looking and looking for a bottom fed reactor, when I saw these I went ahead and bit, have one coming on monday, I was planning to put up a video and intial reaction when I get it going since there isnt much out there yet about these reactors.