hi, first I would definitely not recommend a naso to a 55. IMO it would be very stressed. My naso is one of the smallest I have been able to get at about 4 inches, but now actually a little bigger already. She seems happy. At night she zooms back and forth and in the 4 foot tank, there is definitely not enough for she is fast. I am getting ready to upgrade to a 6 foot tank because of this. I think a 55 would be really hard to have swim space.
My tank has 130 lbs of live rock, I have an eheim 2217 cannister filter (so far has worked out very well but will be going with a sump next time so I can have my skimmer and heaters in there instead of the main tank). I have a remoraC pro skimmer w/ bubble eliminator box with the mag3 pump. I have in each corner...1 900 maxijet pointing up for increased air exchange and then one that comes across in the water to each hit the front of the tank. then in center back I have a maxijet with a rotating thing we put on for movement that works really well. I have had no issues at all with nitrates or anything in my system. I do a quick 10% water change each week and every other week change the filter floss in my cannister which takes all of 5 min.