You can't go wrong with Eheim although the Emp 400 is an excellent filter and will run for years. I also like the Aqua C skimmers, but I would suggest the Pro for a 55
gal tank...the regular Remora isn't enough. You may have some trouble with the pump coming loose as well so you might want to pick up a couple of extra clamps and secure it a little better than it is from the manufacturer.