Undergravel Aquarium Filter

There are three major categories of aquarium filters based on their filtration processes. Basically, there are biological, mechanical and chemical filters. Biological filters remove harmful microorganisms and bacteria from aquarium water. Mechanical filters remove solid wastes while chemical filters remove toxins and other chemicals. An undergravel aquarium filter falls under the biological filters category.

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Biological aquarium filters, such as the undergravel aquarium filter, helps prevent nitrogen embolism. This phenomenon is a result of the nitrogen cycle wherein the water becomes oversaturated by ammonia and other poisonous gases. Too much toxins in the aquarium water can set off fish casualties. To avoid these problems biological filters work in two ways, specifically increasing the surface area for the nitrifying bacteria to colonize and creating a constant water flow over the colonies.

The most popular type of biological aquarium filter is the undergravel aquarium filter. It is a relatively inexpensive form of biological filter. Even so, it has been proven to be both reliable and very effective. This filter typically looks like a plastic plate covering the bottom part of an aquarium. This plate contains a number of small holes. Although the exact physical appearance may vary from one brand to another, all undergravel filters work on exactly the same principle.

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used undergravel aquarium filters, click here

How does the undergravel aquarium filter work? The filter plate is covered with gravel. At the back corner of the filter plate is a lift tube extending from the plate itself to the top of the aquarium tank. The water is then drawn up the lift tube by either an air stone or a powerhead pump. It pulls the water from under the filter plate thereby drawing water down the plate through the gravel. As the water passes through the gravel, the colony of nitrifying bacteria makes use of the dissolved oxygen to metabolize the nitrite and ammonia.

As a result of the bigger surface area and the constant water movement that supports the existence of large colonies, aquariums with undergravel aquarium filter can house ample amounts of nitrifying bacteria for a productive nitrogen cycle and a healthy aquarium environment.

Aside from functioning as a biological filter, the undergravel aquarium filter also acts as a mechanical filter. It can trap solid wastes as they attempt to pass through the gravel bed. However, the water flow through the bacteria colonies is reduced as the spaces between the gravel fill up with solid particles. In the long run, this will significantly impair the effectiveness of biological filtration. For a more efficient aquarium filter system, use a separate mechanical filter to remove solid particles before they lodge themselves on the gravel bed.