Sponge filters have been around almost since aquarium-keeping began. However, many aquarium owners either have no idea what they are used for or don't know they exist at all. Although sponge filters aren't suitable for every tank, there are situations in which they are perfect.
What Are Sponge Filters?
Sponge filters are precisely what the name implies, a sponge through which the aquarium water is drawn. This provides mechanical filtration, and once the sponge has matured and grown bacterial colonies, it provides biological filtration as well. Sponges come in a variety of shapes and sizes, as well as pore sizes. This allows them to be adapted to a variety of filtration needs. They can be powered by a number of methods, including air pumps, powerheads, or even another type of filter.
Using Sponge Filters for Gentle Filtration
Sponge filters are excellent when safe and gentle filtration is needed, such as in a fry tank where young fish could be sucked into the intake of standard filters. Fish species such as bettas that do not thrive in strong currents also benefit from sponge filters. Shrimp are another species that requires very gentle filtration rather than a strong intake that would suck them in. Sponge filters are also great for hospital tanks, where fish are often weak and not able to tolerate the stronger suction from a standard filter inlet.
Sponge Filters for a New Aquarium
Another use for sponge filters is to jump-start a new aquarium. A sponge filter can be run on a well-established aquarium for several weeks or months to establish biological colonies. Once the new aquarium is set up, the matured sponge can be placed in a bag of water and transferred directly to the new tank, thus maintaining the biologicals. This gives the new tank an immediate biological boost, which in turn benefits the fish in the new aquarium by reducing the ammonia and nitrite spikes experienced in a new tank.
I keep a sponge filter in each of my three tanks. In the event of a power outage, I can hook up a battery operatedair pump to them.
So far, I’ve only needed to do that for a few hours but I feel better having the backup.