Sumps are more commonly used on saltwater systems, because a Saltwater tank will usually require a protein skimmer, which usually needs to be placed in a sump to work. You can install a canister on just about any aquarium. A sump needs an overflow of some kind - there are hang-on overflow boxes but they can be a little scary to set up for a beginner. Sumps are best on tank that has a built-in overflow and has already been plumbed for that use. A sump is a great place for filtration because it has a huge amount of volume that can be filled with whatever media your heart desires, but in itself is not a filter.