all you should ned in terms of filter media is biological media such as sponges, bio-balls, bio-max etc etc. Since you will be doing regular water changes anyway, just like every other SW
tank keeper, the build up of nitrogen and phosphorus wont be a problem. If they ever are a problem, something you would determine by testing, then I would suggest using these medias.
As for activated carbon, the only time you should use this is when you are trying to remove medication (ie: copper sulfate) from the tank. Otherwise, since activated carbon is not selective in what chemicals it adsorbs, my opinion is that the AC
would more then likely remove alot of the nutrients your plants need to survive.
Hope that helps.