My old Magnum 300 canister filter had a vertical sort of interior with an 8" tall mesh sleeve (mechanical/biological) that fit over an activated carbon interior core for chemical filtration - at least I think that is more or less how it was set up. It has been 15 years...sigh...where does the time go?
There are at least four or five popular brands from which to choose. Fluval. Nexx. Marineland. Eheim. Etc
Some of them are built like a lunchbox from India...vertical stacking of three shelves. Each shelf houses a filtration media such as floss/pads, charcoal, and bioballs (high surface are to promote bacteria growth for biological filtration).
Depending on the type of fish, you might want to pay attention to the flow rate. Some fish prefer flow, others get blown about a bit. I have heard that Discus don't particularly care for the high flow rate, but I am sure others on these forums might have other opinions based on better experience. I am only regurgitating what I have studied on these forums over the past few weeks.
I see you started another thread on sumps. Good luck, I'll be watching and learning...