Any experts please feel to add, but this is the info i have gained from this site whilst setting up my 20 gallon nano. Are you setting up a nano reef or something bigger. A 6ft tank would not be classed as a nano.
Even though my tank is only a nano my main regret is not having it drilled so that i could have a sump/refugium underneath. This would be something to consider before you start.
What you need, not in order of priority :
Salty water - you can either buy ready made up from your lfs or make your own with a proprietary salt mix and RO (reverse osmosis) water.
Some say that treated tap water is fine for a fish only set up but if you are considering inverts (snails, crabs etc) and corals too even in the future use only RO water. You can get this too from your lfs or buy a RO unit yourself. With a 6ft tank and the water changes required a RO unit will prob pay for itself quite quickly.
Tap water may contain high concentrations of copper and other nasties which lots of creatures find poisonous.
Filtration - this is provided by the living lock (lr). Quoted figures are i believe 1kg per 2 gallons of water, but you will probably need more for good aquascaping. Living rock is around £10 a kilo, but i heard its going to go up sharply due to chage in transportation costs. Mechanical filtration (not including protein skimmer) is reportedly not required as the lr provides the filtration, but i run an external canister filter filled with lr and a phosphate removing bag.
Heating - some method of keeping the water at your chosen temp, either in tank or external. I run a 200w hydor on the outlet of my cannister filter. Keeps the tank tidier.
Substrate - some form of coral sand either living or normal, i bought living cos i didnt know better but having said that after a week or so i did seem to have thousands of pod crawling all over the place. The sand also acts as a buffer to maintain a steady pH.
Circulation - Good circulation is required around the lr in order for it to "filter" properly. Quoted figures are between 10 and 20 times the volume of water in tank per hour. This is normally provided by some form of powerhead or external pump or combination of the two.
I have two korallia 2 powerheads in a 30" tank which i guess is a bit overkill. Getting the direction of flow right took some time as i now have fast and slow areas. All corals in there chosen positions seem very happy.
Lighting - Really depends what your planning to keep and how deep tank is.
Hard corals really need metal halides
Soft corals need what are called T5`S which are high output fluorescent tubes as a minimum
Fish only i think you can get away with T8`s
I bought a brand new arcadia luminaire with 4 T5`s ( 2white and 2 blue) for £80 which i think is a bit of a steal.
Testing kits - hydrometer/refractometer to measure the saltiness (SG) of water, nitrite,phosphate,nitrate,pH as a minimum.
Protein skimmer - will come on to this as research is not agreed on its necessity for a soft coral nano reef.
Off home now so speak later
Cheers
but keep my 5 empty 2 foot freshwater tanks to keep breeding and keep my reef alive 
lol are they known as wavemakers aswell?
