LOL. The name is very intimidating for what they are. The term "reactor" makes it sound like its some high tech thing, but it is so simple.
Tank a clear cylinder tube about 4" diameter. Seal one end, and on the other end have a cap. In the top of the cap there are 2 outlets. One in the center, one on the edge. Now inside the tube there in a small (1/2" tube) running down the center with a plate at the end with a bunch of holes. Ok, this is sounding way more complicated typing it out. It really isnt. So.. you have a tube down the center.. you attach a small pump/hose up to the center inlet, this pumps water into the small center cylinder, all the way to the bottom, then forcing all the water it pumped in to come out the outter area through the holes in the plate. The media, be it carbon, phosphate remover, ammonia remover, etc, is in the outter section and ALL of the water pumped in is then forced through all of the media so every surface of the media gets used. Instead of a bag of carbon that you stick in the sump and hope water goes through it, this forces the water through it. Like supercharging any media you put in it. It makes the media inside look like its dancing because its always in a fluid motion, but not to powerful.
Marine Depot is where I get my media and reactor from.
As far as needing one.. I say ya.. they really supercharge any media you use. Just make sure you get the right pump. In this instance, bigger is NOT better. You probably won't need Phosban media right away, but you can put in carbon/ammonia mix remover.
Wow, I just found
this little gem.. sounds awesome!