Your Emperor is called a HOB filter. (hang on back) of the HOB filters Aquaclear 110 seems to be the fan favorite.
Canister filters are a combo of mechanical and biological filtration. They for the most part are great for mechanical filtration because they force water through a media type and put it back in your tank. They do have their weaknesses, for instance any bio media in a canister has to be 100% submerged. This would limit the amount of BB one could establish. However, media such as Seachem Matrix, BioMax, or Eheim Pro have really negated this and made canisters extremely capable of holding BB.
Lastly you have your sumps. These can be anything from a $300.00 item you purchase to your own personal work of art. I've noticed on MFK most sumps are actually aquariums that are converted into sumps. A sump starts by using filter socks or floss to remove large waste from the water column, this water is then moved to the next stage which could include anything from scrubbies, to BB etc etc. the water would move on to the next stage where it would find a pump to return it to the main tank.
Now, with a sump you have a lot of room to personalize your filtration, you can hide heaters, create a refuge, add algae scrubbers, etc.
Because of this many fish keepers run a sump, however with the increasing availability of in line heaters, in line uv sterilizers many are running canister filtration that out performs some sumps.
Mike
