ok one more question;
I m gonna buy a feather duster tomorrow and wondering if i have to feed them w/ plankton, my friends have them and dont feed them and they are ok also growing but i heard here that you need to feed them, is this a must?
Not really. If you feed frozen foods take your fingers and smash up a few pieces and that will be enough. They filter feed anything in the water column. Just make sure that the feathers wave some or they will jump tube, rooted or not. If you have corals as well you could also do some zooplankton for them and the duster.