Hi guys, just starting out with my new 55gal SW. So far, I'm using my old filter whch are a magnum 350 and a peguin 170. I also have 5lbs of live rock which i got today. Ill buy more later since it so damn expensive. I'm using sand as subtrate? Is there anything else i need for my tank? protein skimmer, R.O....? List the must have and optional if you can. Thanks in advance