It has been way too long since I was into saltwater, so I can't make a recommendation. If you are in the Central Florida area, The Fish Bowl specializes in SW aquariums and they can lead you in the right direction.
I use the Sapphire protein skimmer. U can get it off ebay. I fits where all your bioball go. Take out your bioballs. They do more harm than good. The skimmer u can still close the lid. Read up the whole page on this link