Now using RO water in saltwater tank. Probably somewhere around 10-20 lbs of live rock, two clown fish, two pencil sea urchins, one chocolate chip starfish, nine hermit crabs, one cleaner shrimp, one snow flake eel. brown film is slowly going away. My Q? Is now that I'm using RO water do I need to add anything to the water to keep the eco system balanced such as calcium, proteins etc. RO water has nothing in it so just wondering, or will the system do it all on its owne.