A freshwater tank requires certain equipment to maintain the level of water quality aquarium fish need to survive. In addition to a heating and lighting system, you need to install a quality filtration system in your tank to remove waste products to keep your tank water clean. Aquarium filtration systems come in a variety of different forms, but five of them are our top picks.
What are the Three Types of Filtration?
Before you can understand the benefits and drawbacks of the top five types of aquarium filtration systems, you need to know how they work. When it comes to maintaining a freshwater aquarium, filtration is very important. An aquarium is an enclosed environment so you need a filter to circulate the water so it doesn’t become stagnant, to oxygenate the water so your fish can breathe, and to help remove harmful substances from the water column. There are three types of aquarium filtration:
- Mechanical Filtration – This type of filtration involves removing solid wastes from the water column by forcing tank water through filter media designed to capture particles that are suspended in the tank water.
- Chemical Filtration – This type of filtration involves removing dissolved wastes and toxins from the water column by passing tank water through activated charcoal or other filter media designed to target and capture certain chemicals or nutrients.
- Biological Filtration – This type of filtration is facilitated by beneficial bacteria, and it involves breaking down waste products in a process called the nitrogen cycle that creates ammonia. Because biological filtration is controlled by bacteria, biological filters simply provide surfaces on which the bacteria can grow.
When shopping for an aquarium filter, you have to think about which types of filtration your tank needs. Generally, it is best to find a filter that offers three-stage filtration, or all three types of filtration. Some aquarium hobbyists choose to stock their tanks with more than one type of filter to meet these needs – this is usually done in very large tanks that have a high water volume.
The Top 5 Filtration Systems for Freshwater Aquariums
Now that you understand the different types of filtration, you have a foundation of knowledge on which to build your understanding of the different types of aquarium filter. There are a number of different types of filter, but the top five are described below:
Power Filter
Also known as a hang-on-back filter, the power filter is one of the most common choices for aquarium hobbyists because they are easy to use and very effective. This type of filter consists of a plastic box that houses the filter media as well as an intake tube that sucks water up from the aquarium and passes it through the filter media before returning it to the tank. These filters come in a wide range of sizes, and most of them offer at least two-stage filtration – some models include a bio-wheel component for added biological filtration.
Canister Filter
Another popular type of aquarium filter is the canister filter. A canister filter is an external filtration system that consists of an enclosed canister that contains the filter media with one tube sucking up water from the tank and a second tube returning filtered water to the aquarium. Canister filters are very efficient with mechanical filtration and, depending on the filter media you choose, can offer chemical and biological filtration as well. These filters come in all sizes, and they are particularly good for planted tanks and for very large tanks.
Internal Filter
Generally used for smaller aquariums (less than 20 gallons), an internal filter is one that you submerge in your tank water, attaching it to the side of the tank using a suction cup. Depending on where you place the filter, it can suck up solid wastes before they settle on the bottom of the tank and they can facilitate water movement on the surface if they are hooked up to an air pump.
Undergravel Filter
One of the more outdated styles of aquarium filter, the undergravel filter still serves an important purpose. This filter consists of a slotted filter bed that you place on the bottom of the tank before adding your substrate on top of it. There are tubes on either side of the filter bed that suck water up through the filter bed and return it to the tank surface via an air stone. Undergravel filters offer mechanical filtration and some biological filtration since beneficial bacteria tend to accumulate in the gravel bed, but they don’t offer chemical filtration.
Wet/Dry Filter
This is one of the more advanced types of filtration system, and it is more commonly used for saltwater tanks than freshwater. A wet/dry filter consists of separate chambers, one of which is wet and one which is dry. Depending on the filter media chosen, a wet/dry filter can offer three-stage filtration. This type of filter is particularly beneficial for biological filtration because the wet/dry design cultivates the ideal environment for beneficial bacteria to break down wastes.
In addition to these top five types of aquarium filter, there is one more that is used less often – the sponge filter. This type of filter consists of a power filter where the intake tube is inserted into a sponge, so tank water is filtered through the sponge material before being routed back into the tank. This type of filter is typically used in hospital tanks and fry tanks because it offers gentle mechanical filtration and it requires little maintenance.
Choosing the right filtration system for your aquarium is of the utmost importance. Any of the five filtration systems discussed above can be adapted to different tank sizes, but if you are looking for the perfect combination of mechanical, chemical, and biological filtration with easy setup and maintenance, your best bet is probably a canister filter or a three-stage power filter.