One important factor in having healthy plant life is your filtration system. Stay away from under gravel filters because they produce a steady flow of bubbles that disturb the surface. The filter plate on under gravel filters also limit's the composition of the gravel in which the plants are rooted. All other kinds of filtration systems will work well. This will cause excess build up of toxic chemicals and can kill your fish quickly. As the water in your fish tank cycles through the nitrogen cycle, you may notice that is becomes very cloudy. This is a normal process and should clear up in a few days. Do not add any new fish until the water is crystal clear again. These types of aquariums usually consist of shrimp, prawn, hermit crabs and perhaps even starfish or sea cucumbers. The third type is the fish and invertebrate saltwater aquarium. These are more difficult to maintain than either of the two categories separately. Certain invertebrates feed on certain fish, and the reverse is also true. In order to avoid a costly mistake it is important to be patient, watch the tank closely, and make sure that you don't introduce any marine life until the tank is absolutely ready. Once the aquarium is ready, start with anemones and clown fish. They are the hardiest of reef species, and who wouldn't love to have Nemo swimming around in their living room? It is important to choose fish that can withstand high levels of nitrites and ammonia, because these levels are always high in a new tank due to the nitrogen cycle. Debris in the tank from fish excretions help to generate the good bacteria that is needed in order for the fish to survive. Since there are currently no fish in the tank this will take some time. It will take approximately five bags of rock or other substrate to line the bottom of the tank. Choose a bright color to add some interest to the aquarium. In addition, you will need to purchase a filter for the tank. Filters can be complicated. Do a lot a research to find out what type of filter is suggested for the fish that you choose.