Internal Filters

Internal Filters

The internal power filter is probably the most widely used type of filter and they are available in a wide range of sizes from micro filters, suitable for very small tanks of 18" (45cm) or less, up to large units capable of filtering tanks of 100 gallons (500 litres) or more. The typical internal power filter is a plastic box with slits in the bottom and sides, filled with a sponge media and attached to the pump unit. They are normally attached to the aquarium wall using rubber suckers. When the pump is switched on, tank water is drawn through the sponge media where it is filtered and then pumped back into the aquarium. When placing a filter in the aquarium it is a good idea to situate the filter in such a way that the outlet of the filter is close to or above the water surface. Oxygen exchange only occurs at this level, so ensuring there is always movement increases oxygen levels in the water. Some internal filters come with a space inside the filter chamber where activated carbon can be placed to add an additional level of filtration.