What Kind of Filter for a Hexagon Fish Tank?

Fish tanks come in a variety of different styles, shapes and sizes. Aside from the common rectangular shape often associated with aquariums, they also come in polygonal varieties, including hexagons, where six panes of glass are used. While the shapes may be wildly different from the rectangular aquariums, selecting a proper filter for a hexagonal aquarium is similar to the process for other shapes.

An aquarium filter does just what its name suggests: It filters the water in a fish tank. Many aquarium filters push water through a permeable sack containing activated carbon; this medium filters out dirt and particles, and the carbon absorbs harmful chemicals. Filters also provide a means of biological filtration by providing surface areas for beneficial bacteria, which may ingest harmful materials, to grow. Another function of filters is to oxygenate the water by providing a constant current.

There are three typical types of filters. Hanging filters, the most common, hang on the outside of the back of an aquarium, suck up water via a suction tube, filter it through a filter cartridge (typically a carbon bag) and expel it back into the aquarium via a spillway. Undergravel filters are permeable racks that lay underneath the aquarium's gravel and filter water using a power head. Canister filters are external filters that suck out water through a tube, filter it in an external canister and expel it back into the aquarium with another tube.

Because of the hexagonal aquarium's unusual shape, it is difficult to find undergravel filters that suitably fit. Hanging filters are much easier to find and usually fit on the back of hexagonal aquariums; they are the perfect choice for a medium-sized hexagonal aquarium. Canister filters are the ideal choice if the aquarium is larger than 44 gallons or so, as several hanging filters may be needed to properly filter any amount of water over that. Placing multiple hanging filters on a hexagonal aquarium would be difficult because there's typically only one filter space in hexagonal aquarium hoods.

Most hexagonal aquariums come in small kits, typically with tanks under 10 gallons. Some brands of desktop hexagonal aquariums have built-in filters. These filters may use a spinning wheel that oxygenates water and provides a surface area for the growth of beneficial bacteria. Other brands use tiny undergravel filters, but be advised that these aquariums will require frequent gravel vacuuming.

Freshwater aquariums have much lower filtration demands than saltwater aquariums. When selecting a saltwater aquarium filter, whether a hanging or canister filter, make sure to select an overpowered filter. For example, if your hexagonal aquarium is 29 gallons, select a filter powerful enough to efficiently filter 55 to 60 gallons. The filter's power should be clearly labeled on its packaging.