Types of Filter Systems for Small Aquariums
Filters for Betta and Goldfish Tanks and How They Work
Oct 29, 2009
Even small aquariums, betta tanks and goldfish tanks can benefit from a good filter. Here's the lowdown on what types of filters are available, how they work and which are best for sensitive fish like bettas!
Types of Aquarium Filters
Here's a very simplified rundown of the most widely-available types of filters:
Hang on Back Filter (HOB): This filter, as the name suggests, hangs on the back of the fish tank or aquarium. The water is drawn up into the filter, and filtration takes place outside the tank. The filter doesn't take up space inside the tank, but may make it difficult to place the tank close to the wall.
Hang on Tank Filter (HOT): This kind of filter hangs inside the tank, with an air pump outside the tank that provides the air current to filter and aerate the water. All filtration occurs inside the aquarium, which takes up less space.
Undergravel Filters (UGF): These filters often come with aquariums, especially aquarium kits designed for beginning fish owners. UGF kits draw aquarium water down through the tank's gravel substrate. Just vacuum the substrate with an aquarium vacuum - or even a turkey baster - to remove larger particles of fish waste and other debris.
Types of Filtration
There are three types of filtration systems to use with aquarium filters:
- Mechanical Filtration: Removes the particulate matter from the water. HOB filters do a pretty good job of this type of filtration.
- Chemical Filtration: Removes dissolved wastes from the aquarium. Often, activated charcoal is used for this type of filtration, but charcoal filters need to be changed often or they will simply release the wastes back into the water once they are full.
- Biological Filtration: Biological filtration is usually used in larger tanks because it requires growing beneficial bacteria in the filter; the good bacteria converts ammonia to nitrite and then converts nitrite into nitrate. However, biological filtration is most often used in larger tanks that have an existing nitrogen cycle - not smaller tanks that get a 100% water change every two weeks.
Filters are a must for goldfish, which produce a lot of waste to clean up and need well-aerated water - and filters can help with both of those needs. Betta fish don't need so much filtration or aeration unless they live in a community tank, but filters are helpful as long as the current they produce isn't too strong for the betta.
When a Filter is Too Strong for Betta Fish
Most fish aren't affected by filter currents - but bettas, with their long fins, sometimes are. Some bettas love the challenge of swimming against the current a filter produces, and others are bothered by even the most gentle filter.
If the filter is too strong, try decreasing the strength of the current in one of these ways:
- Cut the toe out of a pair of pantyhose and put it over the filter's intake tube. Secure it there with a rubber band. This will slow the intake a little - and thus the current.
- Add silk plants, real plants or soft plastic plants (that don't have jagged edges to tear the betta's fins) or a "cave" for the betta to hide in when he needs a break from the current.
- Create a surface barrier. Buy a plastic mesh tank divider kit, cut a long strip of mesh that's about two inches wide, and attach the mesh strip to the brackets that came with the kit. Attach the brackets to the tank at the surface of the water, around the flow output from the filter, with a little of the mesh poking out above the water. This creates a calm place for the betta to rest. (Thanks to the Nippyfish Blog for this advice!)
So that's the skinny on the most common types of filters available for smaller fish tanks such as goldfish and betta fish tanks. For more specific advice on filters for betta tanks and betta tank setup, see Choosing a Filter for a Small Betta Fish Tank.
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