The next thing to think about is the nitrogen cycle. The real ocean keeps itself clean; but even in the largest home saltwater aquarium, your water needs help. The first step is putting your new, clean, salty water through the nitrogen cycle. For six weeks, you must leave only one or two fish in your tank as bacteria from the air will start to make its home in the water. These bacteria are important because they change fish waste into inert chemicals. The bacteria are clear and clean, but you must wait for them to grow.
Saltwater Aquarium