There are a lot of different choices, a lot of them work quite well, it pretty much boils down to personal preference. There are three basic types:
1) Mechanical- strains out particulate
2) Biological- breaks down ammonia(very harmful) into NitrIte(also very harmful), and NitrIte into NitrAte(which is still harmful, but not as harmful as the first two, and at much higher concentrations)
3) Chemical- removes toxins by absorption
1 & 2 are basically necessary and inexpensive long-term. 3 is expensive if used long term and really not necessary if 1 & 2 are doing their jobs. It comes in handy to remove meds, though and can help in an emergency, if you get an ammonia spike for some reason.
All commercial filters perform at least 1 & 2, and often all three, just in slightly different ways.
EDIT: Minimum recommended turnover is 4 to 5 times the tank volume per hour(4X55= 220 G.P.H.)
Many people prefer a higher turnover(I'm one) 10 to 12 times is actually my preferred rate of turnover.