ok the way i see frag tank is that it has to be almost better than you display tank as you are propagating and growing out stuff so you want good levels of all the elements and a very good lighting and filtration, this isnt something you throw together half hearted or "half wallet" lol. i would suggest some type of fuge or sump/fuge and a good skimmer and such. you want to feed your coral and be able to transport waste out fast.