Marine Aquarium Filtration
There is a dizzying array of filtration options for fish tanks, though those used for marine aquarium filtration must meet stricter tolerance requirements. Choosing a filtration system will have a great deal to do with the size of your tank, what you plan on keeping in it, and whether or not you will want equipment hanging off the side of the tank.
Generally, when considering marine aquarium filtration, one must consider exactly what they hope to accomplish with it and the needs of their "livestock." A healthy marine ecosystem will have more than ample filtration to handle any bumps in the solute load. They come in three basic types:
- Chemical
- Mechanical
- Biological
There are many permutations of each, but it is recommended that you use at least two different types. Many all-in-one filters employ two filtration approaches for better reliability.
Chemical
This often takes the form of activated carbon. It chemically binds to solutes in the water and removes them from solution. These are effective as long as there are free binding sites. When a carbon filter stops working, it does so rather quickly. Because of this, many carbon filters also have a biological component.
These can require frequent changing and expensive ingredients to maintain, and are usually thought of a secondary system. They are also very commonly used with very sensitive species.
Mechanical
Often used in conjunction with one of the other types of marine aquarium filtration, this method relies upon catching precipitated materials in a mesh trap. This is very effective with solid wastes that can build up and would otherwise need to be suctioned out. It does require that sufficiently small filter diameters be used, and this can require a fair amount of energy to run the pumps.
This is most commonly seen as a primary stage of a biological filter, and is sometimes used in conjunction with less effective biological systems such as the under-gravel method.
Biological
Probably the most important aspect of aquarium filtration, biological filters all work according to the principle of increasing the available surface area for beneficial bacteria to cling to and colonize, allowing these living microbes to actually digest the waste products right out of the water while keeping other unfavourable bacteria and fungus from colonizing.
This may require a mesh substrate in a filter, or it could even be living rocks and sand that support life as the ocean floor would. This type of marine aquarium filtration system works best in larger aquariums, but should be at least one component of any saltwater set-up.
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