Power or Hanging Filters
Filtering your Aquarium Water
(The First Tank Guide)
What Is a Power Filter?
Power filters, also called hanging filters or overflow filters are often sold with inexpensive aquarium kits. A hanging filter is any filter that hangs off the back of the tank and draws water in through a lift tube and returns it through a spill-way. Power filters are any hanging filter with a water pump to move the water.
How Does a Power Filter Work?
Power filters draw water up a lift tube and into a filter chamber where the water is pushed through a series of filter media (bottom-to-top or back-to-front, depending on filter model) which can provide chemical, biological, and/or mechanical filtration (depending on the media used).
After the water has gone through the filter media, it flows over a spill-way or overflow and back into the tank. The water is moved either by a water pump which pulls water through the lift tube or by air bubbles (from an air pump) that lift water into the lift tube and over into the filter box.
What Maintenance Does a Power Filter Require?
Depending on the brand and model of the filter, and the type of media used, the maintenance requirements of a power filter vary. Many power filters use manufactured filter cartridges that fit the specific model of filter you have. These cartridge can be rinsed out when you do water changes to remove accumulated debris, however, they need to be replaced frequently. Sponges used in power filters should not need to be replaced until they start to deteriorate, just rinse them thoroughly in dirty aquarium water as necessary. Carbon or zeolite cartridges should be replaced frequently to prevent release of toxins into the water. Remember to remove any carbon from the tank or filter before you medicate (if the carbon is working, it should remove the medication from the tank in under an hour, in which case your fish won't get treated).
In addition to the maintenance required for the filter media, you also have to periodically clean the lift tubes and the pump on your power filter. This can be done easily with aquarium tube cleaning kits sold at pet stores.
What Should I Be Aware Of with a Power Filter?
Power filters can be inefficient. One reason is that they normally have their intake directly below the spill-way, therefore a significant portion of the water being drawn into the filter for cleaning is the water that has just been returned to the tank from the filter after cleaning. Power filters also lose water, not by spilling it or leaking (though either can occur with any filter that involves the water leaving the tank...), but because when the water is returned to the tank, the surface area is greatly increased, allowing a large amount of evaporation. Also, these filters require that a large area cut out of the top so that the filter can be mounted on the tank, this increases air exposure and encourages evaporation. On the positive side, the increase in surface area will also improve dissolved gas levels, keeping the oxygen available to your fish closer to the amount available in the air. This opening in the aquarium top also provides an escape route for jumping fish or for any amphibians or crustaceans you have in the tank.
Many power filters use filter cartridges manufactured for a specific model of filter. Unfortunately, this often means that every time you have to change the filter media, you have to remove most of your biological bacteria bed, causing your tank to cycle again. To avoid this, when selecting a power filter for your aquarium, make sure you are getting one that takes multiple pieces of filter media, or has some permanent filter media attached or built in to the filter so you do not have to change all the filter media at any one time. Power filters make good particulate filters, and can be set up as either poor chemical filters or adequate biological filters.