Now that you have chosen and purchased your new aquarium, stand and hood, you will need to select a filtration system, if you haven't already purchased one with your new tank. To make this decision, there are two things to consider. Do you want a Fish-Only tank or a Reef System tank?
There are a number of basic components that are required to run either of these systems. With the wide variety of aquarium filtration systems on the market today, filter selection can be mind boggling. The most popular filtration system today is the wet/dry type. You can find compact power filter wet/dry units that hang on the outside of your tank, to the more advanced wet/dry trickle, bio systems (bio balls, bio beads) using a sump, ultraviolet, protein skimmers, and so on.
For a fish-only tank remember, fish have the natural trait of cruising, eating and picking foods all day long. If you were to put natural live rock, corals, algae and plants (a reef system) in your tank with too many non-friendly reef species of fish, in a very short time you would no longer have "live rock", you'd just have rock. This is particularly true with fishes from the Surgeon and Angelfish Families, which are primarily herbivores, or the Butterfly Fish Family, which are primarily coral eaters. In the wild, these fish have an unlimited source of food to pick from, however, in a closed system they could quickly wipe out your reef system investment. If you want fish, keep it simple. Some sand or gravel media for the bottom of the tank with a nice arrangement of rocks, corals (cured) and shells where the fish can establish a house of their own. Be sure to supply sufficient cover for all of your fish so they are comfortable and don't have to compete for their own territory because of a "housing shortage".
For the standard size fish-only tanks (55-75 gal.), we recommend a basic Undergravel Filterplate (U.G.) filter with an air pump and stones. It is easy to set up, easy to maintain and relatively inexpensive. There are fewer plumbing and gravitational problems (water ALWAYS wants to flow downhill). The U.G. filter acts as both a mechanical (traps solids) and a biological (provides a large surface area for bacteria to grow on) filter. When considering your air pump, be sure to get one strong enough to draw sufficient water through your filtration system for the size of your tank, but not overpowering. With a simple once a month maintenance program, consisting of a partial water change (20%) and cleaning your media base, this basic set-up runs efficiently. For your larger aquariums, 100+ gallons, your fish-only tank can be set up without an undergravel filter. For your filter system you can use a wet/dry trickle bio-media filtration set-up, power heads for circulation in the tank and a protein skimmer.
For the more diverse (Live Rock Filtration & Berlin Set Ups), you can have all the "natural" beauty of the ocean right in front of your eyes. With the reef system your live rocks, corals, plants, sponges, anemones, etc., will act as your biological filter, so a filter bed base (gravel/sand on the bottom of the tank) is not required, unless you desire a thin layer for looks. For your mechanical filter you can use a wet/dry trickle set-up as mentioned above. You can include a few fish, but be sure to pick fish in size and numbers that will not interfere with your "closed" natural reef system. Reef friendly invertebrates are a perfect contribution to this type of environment too. To help you with what types of fish and inverts to include in your tank, we will detail this topic in our feature article next week.