Marine Tank, Marine Aquarium

The succes of keeping a marine aquarium is measured not only by the length of time its inhabitants are kept alive, their health, and the sparkling clarity of water, but also by the number of breedings being reported. This number has increased tremendously in recent years, and as more attempts are being made inthis direction it is sure to continue. To keep a marine aquarium functioning properly for months or years is not as difficult as some people make it out to be.

The most important piece of equipment you will have to buy is of course the tank. It should be an all-glass tank with no metallic parts whatsoever. The size of the tank is very important. Although the temptation to buy a less expensive small aquarium may be very strong, nothing less than 25 gallons should be considered, and a 50-gallon tank would be ideal for a beginner. The reason for this is simply that the larger tanks are easier to maintain. A small tank can foul more easily, and once the process has started it is almost impossible to stop it before everything has succumbed. In a larger tank you have less chance for serious pollution to occur and generally have sufficient time to try and correct any problems that might crop up.

The shape of the aquarium must also be considered carefully. Of great importance to the well-being of the tank inhabitants is the surface area. The greater the surface area the better. It is the surface that most of the carbon dioxide that is respired by the animals and plants leaves the water. Tall, narrow tanks with limited surface area can contain fewer organisms (such as fishes) than low, broad tanks of the same volume but with a greter surface area.

Pumps & Filters

To run all the filtering equipment and airstones, you will need a pump. Since the lives of your fish depend upon this pump, do not skimp on its quality. In fact, it is a good idea to purchase a second pump as a backup; this one can be less expensive since it will probably be used only in emergency situations and for short periods of time.


Probably the most controversial piece of equipment you will need for the marine tank is the filter (or filters as the case may be). Some people swear by the undergravel filter, others by a canister-type power filter, others by a box-type outside filter (power or non-power), and still others by a combination of different types. Regardless of the style of the filter, the important factors are the abilities to mechanically filter out the detritus and to break down through bacteria the waste materials (the biological filter).

Undergravel Filter

An undergravel filter is just what the name implies. It covers the bottom of your tank from wall to wall and is covered with the gravel. There is a space between the filter and the bottom of the tank, and the filter itself is slotted to allow passage of water but not the gravel. The idea is to draw the water through the gravel to the space below the filter so that the filtering medium is the gravel itself. The water passing through the gravel also prevents pockets of anaerobic decomposition (usually foul-smelling and black in color) from forming. The filtered water from the bottom of the tank is returned to the surface through air-liftes built into the bottom filter. These are usually positioned at the rear corners of the aquarium for esthetic purposes, since they can be hidden from view with various decorations.

Outside Filter

The outside box or hanging filters are basically boxes containing the filtering medium that are hung on the edge of the aquarium. Water is air-lifted from the filter into the tank; this is replaced by a siphoning action from the tank into one section of the filter box. The water must then pass through the filter medium before reaching the area where it is air-lifted back to the tank.

Both the box-type and undergravel-type filters come with motors attached that replace the simple air-lifts. Such motorized filters are called power filters. They move a much greater amount of water through the filter medium than the air-lift, the filtering action increasing accordingly.


The water most aquarists now use is a synthetic product obtained by mixing a package of prepared salts with tap or distilled water according to a specific instruction. The water is added to the tank slowly and carefully at first so as not to disturb the gravel. When about one-fourth to half of the tank has been filled with water, the decoration can be added.


Coral which has been thoroughly cleaned is the most widely used decoration for the marine aquarium. It is a natural product of the sea, it looks good, and its carbonate content will contribute to keeping the pH of your water at its proper level. Most of the coral is placed along the back and sides of the tank in pleasing combinations and positions that allow room for tank cleaning and fish chasing when necessary without undue destruction of the decor. Sea shells are often used to supplement the coral, but they must be thoroughly cleaned and water must be able to circulate through them to prevent pollution from forming or entering the tank unseen. Now, you are ready further in setting up your tank.

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