9 Aquarium Filter Types for Your Fish Tank

Having a fish tank can be a fantastic addition to your home, but it comes with a lot of maintenance. One of the essential parts of maintaining a fish tank is choosing the right filter. In this article, we explore nine different types of aquarium filters, weighing the pros and cons of each, and offering some personal experiences.

Why do Aquariums Need Filtration?

Filtration is an essential aspect of maintaining a healthy and clean aquarium for your fish. Without a good filtration system, waste products such as uneaten food, fish excrement, and dead plant matter can accumulate in the fish tank.

This accumulation can lead to toxic levels of ammonia, nitrite, and nitrate in the aquarium water, causing stress and potentially harm to your fish. It’s through the process of filtration that these toxins are neutralized and your fish can live a healthy life.

To create and maintain a suitable environment for your aquatic friends, there are generally three types of filtration you need to consider:

• Mechanical filtration: This type of filtration physically removes suspended particles from the water, like uneaten food and fish waste. It usually involves a sponge or filter pad that traps debris.
• Chemical filtration: This involves using activated carbon or other media to remove dissolved substances from the water, such as chemicals, medications, and odors. It is an optional type of filtration but can prove helpful in certain situations.
• Biological filtration: This type of filtration is arguably the most crucial in maintaining water quality. It supports the growth of beneficial bacteria that convert harmful substances like ammonia and nitrite into less toxic nitrate. This process is called the nitrogen cycle and is key to a healthy aquarium.

Each of these types of filtration plays a vital role in maintaining the overall health of your aquarium. However, it is not enough to rely on one type of filtration. An efficient combination of all three types is crucial in ensuring a stable environment for your aquatic life.

Filtration is also helpful in maintaining water clarity. It is essential to remember that clear water does not always equal clean water, but it does make it easier to observe your fish and plants, as well as any potential signs of illness.

Another reason filtration is necessary for aquariums is to promote good water circulation. Proper water movement helps distribute nutrients evenly throughout the tank and ensures that all regions of the aquarium receive enough oxygen, as well as preventing the growth of harmful algae blooms.

Sponge Filter

One of the most common aquarium filters is the sponge filter. A sponge filter consists of a foam sponge, air tubing, and an air pump. As the air pump runs, it creates suction, drawing the water through the foam sponge, and filtering out debris and bacteria.

Pros

• Sponge filters offer excellent biological filtration due to the size and shape of the foam. Small pores in the sponge provide a large surface area for beneficial bacteria to colonize, keeping your tank clean and healthy.
• They’re straightforward to set up and low cost, a perfect option for beginners or small tanks.
• Sponge filters are gentle on fish and invertebrates as there is no strong current.

Cons

• Sponge filters are not ideal for large aquariums as they are not powerful enough to keep a tank clean.
• They require regular maintenance. The sponges need cleaning periodically to ensure they don’t become clogged and stop working effectively.
• Because they function by suction, sponge filters rely on an air pump. This means an additional device that can be noisy, though modern air pumps can be relatively quiet.

As someone who has owned fish tanks for several years, I can attest to the effectiveness of sponge filters. They’re straightforward to maintain and never disrupt the fish’s delicate environment.

The only major downside I’ve experienced is the noise of the air pump. However, investing in a high-quality pump is worth the added expense to reduce background noise in your house.

Hang on Back Filter

Another popular type of fish tank filter is the hang on back (HOB) filter. They hang off the back of your aquarium and use a motor to suck water into the filter media, where impurities are removed before the water is returned to the tank.

Pros

• HOB filters are excellent for beginners, as they can handle a wide range of aquarium sizes and are straightforward to install.
• They offer a great deal of flexibility as they can be customized with different filter media types to optimize filtration.
• They come in various sizes and flow rates, making them suitable for different types of tanks.

Cons

• HOB filters can be unsightly and may not be ideal for display aquariums where aesthetics are important.
• They can be noisy due to the running motor, which might be a problem if the tank is in a living area.
• The impeller can potentially get clogged or damaged, rendering the filter useless until repaired or replaced.

I’ve used HOB filters in the past and have found them to be dependable and efficient. They’re a reasonable price, which makes them an excellent option for anyone starting in the hobby. My only issue was the noise, which I resolved by purchasing a higher-end model that operated a lot quieter.

Overall, I’d recommend HOB filters to anyone, and I still use them in my smaller aquariums today. The best part of these filters is that they’re highly customizable, so you can achieve your desired water conditions.

Underwater Filter

As the name implies, an underwater filter is submerged in water, typically in the corner of your aquarium. They use a motor to pump water through a filter cartridge and return it to your tank.

Pros

• They’re compact and can be concealed in your aquarium behind plants or decor, making them an excellent option for display tanks.
• Underwater filters are quiet, and due to their location in the tank, no noise is emitted.
• They are low maintenance and, due to their filter cartridge, can be replaced entirely when it becomes clogged.

Cons

• They may not be suitable for larger tanks, as the flow rate may not be strong enough to filter all the water.
• The pumps can wear out after prolonged use and require regular cleaning.
• Compared to other filter types, they may not offer as reliable or thorough filtration, especially for heavily stocked aquariums.

Personally, I’ve found underwater filters to be best suited for smaller, less heavily stocked aquariums. They’re a great option if you want to hide your filter from sight or keep your tank as quiet as possible.

However, if you have a large, densely stocked tank, an underwater filter may not provide enough filtration for the water volume. I once used one in a semi-aggressive aquarium, and although it functioned well for a while, it eventually became clogged, and I had to replace it.

Overhead Filter

An overhead filter is one of the more unusual filter types, but it is still a viable option for a fish tank. As the name suggests, the filter is mounted above your aquarium, allowing water to flow down into the filter media and then back into the tank.

Pros

• Overhead filters are a great option for display aquariums as they are out of sight and barely noticeable.
• They offer excellent mechanical and biological filtration, making them suitable for all types of aquariums.
• The filter media can be customized to optimize filtration in your tank.

Cons

• Overhead filters are typically more expensive than other filter types due to their design and materials.
• Installation can be more challenging than other filter types, especially when mounting it correctly above your aquarium.
• If not configured correctly or regularly maintained, an overhead filter can cause water to overflow from your tank, leading to potential damage.

I have never used an overhead filter myself, but I have seen them used in display aquariums with excellent results. They are important for display tanks, especially if you want to keep equipment out of sight and ensure your aquarium looks maintained without seeming too cluttered.

However, their cost may be prohibitive for some aquarists, and maintenance can be burdensome if they need adjustment in the future. Ultimately, the choice of whether to use one will depend on your aquarium size, species requirements and its aesthetic value, combined with your budget and skill set.

Canister Filter

Canister filters are one of the most powerful filter types available for fish tanks. They sit outside the tank and use a pump to move water from your aquarium through the filter, before gravity returns the clean water to the tank via an outlet.

Pros

• Canister filters are efficient at mechanical and biological filtration, making it an excellent option for large, heavily stocked aquariums.
• They are customizable, utilizing a variety of filter media to target specific impurities, making them an excellent option for specialized tanks.
• They are low maintenance compared to other filter types, only requiring occasional cleaning of the filter media.

Cons

• They can be noisy, especially if installed incorrectly or if the pump is too powerful for the water flow required.
• They are often expensive compared to other filter types, and their running costs can be high.
• Canister filters are typically large and bulky, so finding a suitable place to install them can be challenging.

I currently use a canister filter in one of my aquariums and have found it to be dependable and robust, keeping my water crystal clear, even with a high bioload. One of the benefits of a canister filter is the customization of filter media to target specific water impurities.

While they can be noisy, taking the time to install them correctly should lead to a quiet aquarium. The upfront cost can be significant with this type of filter, so it is recommended to ensure it’s the right fit for your needs before purchasing.

Undergravel Filter

An undergravel filter is installed beneath a layer of substrate in your aquarium. Air stones or powerheads push water down tubes placed in the filter plate, which then pushes water up through the substrate, allowing biological filtration to occur.

Pros

• Undergravel filters are the most cost-effective option, requiring only an air pump for operation.
• They are low-maintenance and can be left for long periods without cleaning.
• With the substrate acting as the filter media, they are great for planted tanks as it can promote healthy root growth.

Cons

• They are not suitable for all aquariums, particularly those with large fish or heavy plant life as digging and rooting can disrupt the substrate layer and harm the filter.
• Because it uses the substrate as filter media, it can be challenging to clean the chamber beneath the plate ultimately, resulting in reduced efficiency over time.
• They do not offer the same mechanical filtration as other filter types, leading to potential debris building up in the aquarium.

I used an undergravel filter many years ago and found it to be a mixed experience. While it was very affordable and low maintenance, I noticed that debris built up under the substrate layer, leading to foul smells and reduced the water quality.

For those on a budget, it is a good starting option for smaller or less-demanding aquariums. It is also ideal for planted tanks, providing optimal growing conditions. However, it is crucial to choose compatible species with an undergravel filter, ensuring the substrate layer remains intact and efficient filtration is successful.

Surface Skimmer

A surface skimmer is an unusual type of filter designed to remove debris before it sinks to the substrate. They sit on the top of your aquarium, using suction to draw water through a filter cartridge, helping to prevent a build-up of debris on the water’s surface.

Pros

• They are compact and discreet, making them a great option for display tanks.
• Surface skimmers are energy-efficient, requiring little power to run.
• They are effective at removing organic debris from the water’s surface, improving water quality.

Cons

• They’re not ideal for heavy bioloads, as the filter cartridge needs to be replaced frequently.
• They offer limited mechanical and biological filtration and work best when combined with another filter type.
• Pump noise may be present, especially if the water level is not maintained correctly.

I have never personally used a surface skimmer, but I have friends who have had great results with them. One of the benefits of the surface skimmer is the discreet way it operates without interfering with the aquarium’s aesthetic. The drawback is that they do not offer comprehensive filtration, and it’s best to combine them with other filter types to ensure healthy water conditions.

Their effectiveness is impressive, even with just small power input and the need for infrequent maintenance. Ultimately it is a decision based on tank occupants, its size, and if additional filters are required to work alongside this product to acquire an optimal environment.

Sump Filter

A sump filter consists of a separate tank underneath your aquarium that holds the filter media and a water pump. Water drains from the main aquarium into the sump tank, passes through the filter media before being pumped back to the main aquarium.

Pros

• Sump filters offer excellent filtration, making them a great option for large aquariums with a heavy bioload.
• They can be customized with different filter media to achieve precise water parameters.
• They offer a discreet way of housing equipment like heaters and protein skimmers.

Cons

• They require more significant upfront investment to buy the sump, pump and filter media than many other filter types.
• Installation can be complicated, requiring knowledge of plumbing.
• Because of their location outside the main tank, leaks in the pump or plumbing could cause significant damage.

I’ve never attempted installing a sump filter myself but have seen wonderful results. They are the most efficient filter types available, offering unparalleled biological and mechanical filtration. The primary selling point of sump filters is their ability to house equipment like heaters and skimmers, keeping them hidden from view.

Maintenance is only required for the filter media, which is relatively straightforward. They can be expensive to install, especially if getting professionally installed, but the long-term benefits provided balance this out. If you’re looking to create a perfect environment for your fish and other aquatic species, a sump filter is an excellent investment.

Wet/Dry Filter

A wet/dry filter, also known as trickle or biological filters, make use of a long, narrow box filled with filter media, such as bio-balls. Water is pumped into the box, trickling down and creating oxygen-rich contact between water and air. Beneficial bacteria colonize the media, removing impurities and creating high-quality water for your fish.

Pros

• They are among the most efficient biological filters, great for aquariums with a heavy bioload.
• Wet/dry filters offer excellent water circulation, promoting efficient oxygen exchange.
• They are durable, with filter media lasting up to 2 years before replacement.

Cons

• They are relatively expensive, with greater upfront costs than many other filter types.
• They are not suitable for all aquariums as they can create significant levels of noise due to the trickling of water.
• Installation can be more challenging than other filter types, requiring knowledge of plumbing and necessary components.

I have experience using a wet/dry filter, and its efficiency makes it a great choice for larger aquariums. Because of their ability to handle heavy bioloads, they are ideal for species like cichlids which produce a significant amount of waste. Although I have found them to be relatively noisy due to water trickling noise, they provide fantastic biological filtration and are worth considering.

In terms of maintenance, I’ve found them to be among the most straightforward filters to maintain, with their filter media requiring replacement only every couple of years. The initial cost of purchasing the components required, such as the sump, pump, and filter media, does make them a costly investment, but it is worth it in the long-term maintenance and savings.

Conclusion

Choosing the right aquarium filter can make all the difference in keeping a healthy and thriving environment for your fish and aquatic pets. With these nine filter types at your disposal, consider your budget, aquarium size, bioload and other requirements for your specific tank. Which filter type is your preferred choice? Feel free to leave a comment below.