Filtration and Aeiration
The basic equipment for a marine aquarium is similar to equipment needed for a freshwater aquarium. The most important pieces of equipment are the filters, responsible for the purification of the aquarium water. Various types of filtration equipment are available, each performing single or multiple functions. Some filter equipment is optional, while others are an absolute necessity for purifying the aquarium water.
Protein Skimmers - or foam fractionators as they are best known, are one of the most efficient means of removing dissolved organic materials from the water. Although there are various designs for protein skimmers, the basic principle remains the same. As air is added to the reaction chamber, the small bubbles produced by an air diffuser come into contact with dissolved materials. The bubbles carry the attached organics to a surface chamber, where they form a foam. The foam continues to build until the volume of foam is forced into a dry collection chamber, where it liquefies. The organics are disposed of once a sufficient amount has accumulated.
In order to purify your aquarium water it will be essential to obtain filter equipment to perform biological, mechanical, and chemical filtration. There are numerous types and designs of commercial filters for aquariums. The basic types of filters fall into the following categories: undergravel (subsand) filters, outside power filters, canister filters, and the new nitrifier/denitrifier filters.
Filter Materials
Activated Carbon
The Most commonly available filter medium to remove dissolved organic materials in the water is activated carbon, which is manufactured from various materials including coal, and wood. Activated carbon is not the same as charcoal, which has a limited ability to remove organics and should never be used in marine aquariums. Most of the filter media commercially available are high-grade activated carbon.
Filter Floss
Filter floss is primarily a mechanical filtrant but also becomes a biological filtrant as nitrifying bacteria colonize the filter strands. The filter media are generally synthetic materials such as dacron or polyester. Enough material is simply layered in a box filter, outside or canister filter. The mechanical filtrant is also available as pre-sized and layered pads that are simply added to the particular filter used.
Air Pumps and Diffusers
Besides filtration, some additional source of aeration is recommended to promote additional gaseous exchange and to help in providing a current. Marine animals, particularly invertebrates, benefit from aeration, which in turn assists good water movement.
A high-quality air pump is also required for powering undergravel filters. Various types of air pumps are available: the majority are the vibrator type. These tend to be relatively quiet and maintenance free. It is important that you do not economize on the air pump, especially if you intend to connect it to outer pieces of aquarium equipment. Even if the pump supplies more air than needed, the amount can be regulated with valves. There gang valves channel air to various pieces of connected equipment through flexible plastic tubing.
Air diffusers or air stones are useful for providing additional aeration and more water current. As long as ample filtration is provided through good quality filters, there will be sufficient water movement and aeration. However, you may wish to add an air stone or additional water movement.
Ozone Generators and Ultraviolet Sterilizers
The use of ozone and ultraviolet sterilizers will effectively remove dissolved organics in marine aquarium water, and are also effective in destroying agents responsible for fish diseases.
The units generate ozone, a form of oxygen that is a highly energized form of three oxygen molecules. This form of oxygen is capable of oxidizing, or breaking down, various chemical compounds and destroying disease-causing microorganisms. The major disadvantage of ozone is that one must maintain a narrow acceptable concentration because ozone's toxicity to fish and other aquatic organisms. Secondly, the amount of ozone in water is not easily measured not easily regulated, making it virtually impossible for an aquarist to know if the concentration in the aquarium water is approaching toxic levels. Therefore ozone gas must never be added directly to water, but to a reacting chamber first before the treated water returns to the aquarium. Various small ozone generators are available commercially for marine aquariums. With this in mind, ozone should be considered an option, especially for a person new to the marine hobby. Marine aquariums can operate well without ozone generators.
Ultraviolet sterilizers primarily control the concentration in the water of bacteria, viruses, and fungi, all potential causes of fish disease. Irradiation is best used in larger aquariums with large numbers of fish, in which the system can benefit by reducing the buildup of microorganisms.
Various types of units are available commercially. Since many factors play a role in the efficacy of this type of equipment, it is important to select the proper type of unit.