Since the 55g is so long I always recommend using 2 filters, one on each end.
Sent from my SGS4 Active
Yep. For a 55g, twin Aquclear 70's, or a canister and an AC70. Lots of options.
Don't forget glass tops if you're not going with standard T8 hoods.. and a ~200w heater. Keep in mind, mail-order tends to be a lot cheaper for aquarium hardware than a LFS.