the obvious would be lighting which can cost up to 700$ then your going to need to do resurch remember that to have a reef tankyou need less fish as for live rock and filter you should be very carful getying live rock and curing it and if your geting live rock i suggust you just use the powerheads and have it cycle through the live rocks otherwise the filter will take the plankton out thats another thing you need plankton and make sure you place away from temp changers and if you are in a hot climate you need a cooler
I suppose the purposes are different. For example, Vitamen C in oolong tea(in can or PET bottle) are used for preventing tea from oxydizing.(as additives) On the other hand, supplement V.C are usually used for your health.(i.e. protect your body from oxdizing or stress.) (as supplement)
