for your 6footer...u need a powerful skimmer....u dun really need an external cannister, if u have a sump tank below...i would recommend deltec rather than the china made brand or u can consider skimz from aquamarin.
fyi, LED technology is still quite costly...esp for your tank size....and u probably need T5 to complement your LED....so be mentally prepared to fork out an investment....but having said that, if you are keeping mainly fishes, then u dun really require very strong lightings.
n also consider a tank maker that can provide reliable post-sales support for you, in case anything happen, or u need help...