A phosban reactor is a flow through type system that makes many types of media (specifically phosphate media) more efficient in that the water surrounding the media is constantly being exchanged. I have two, one for phosphate media and one for carbon. I find the use of carbon in a phosban reactor simply amazing, it works so much better than just floating a bag in the sump.
I doubt a phosban reactor would do anything for a cycling tank as the rock is usually fairly new and you aren't adding any phosphates (in the form of fish food) to the tank yet. Unless you are getting previously used rock that is leaching phosphates into the water I doubt it would provide any benefits.
Jeez I just read this over and I need to stop reading scientific papers, I sound like I have a stick up my butt
