The difference being suspended media doesnt allow for any debris settlement (common to sumps!) on the media that would otherwise take up valuable B.B. real estate. Essentially a fluidized bed filter.
Agreed, typically it is in a section of the sump by itself, that is designed in a way to allow water to flow through but keep the media in place. This section is kept in a constant state of motion via airstones or powerheads. The media is constantly moving and knocking into itself, which provides 2 functions.
1. It keeps it clean of any debris so no cleaning maintenance is required
2. It will knock off older less efficient BB so that newer more efficient BB can grow.
I don't have any experience with Bio Flo 9, or K1 in general. But I have 6 gallons of K1 that I will be using in my 55g sump for my 135g. I am hoping the airstones I ordered come in the next few days, and I will take some pictures and post em.