How to choose the best aquarium filter for your fish tank

Whether you keep two or twenty fish, aquarium filters are essential for healthy fish tanks. They clean, purify, and aerate the tank water, ensuring a habitable environment for aquatic life.

However, choosing the best aquarium filter for your needs can be challenging, with various filter styles, shapes, and sizes. What’s more, several factors must be considered to ensure you choose the right one for your fish tank, from the size of your aquarium to how many fish you want to keep.

Read on as we share our top tips on choosing the right aquarium filter for your needs, including the best ones to buy at Pond Planet!

Table of contents

  1. Why do you need an aquarium filter?
  2. What are the three main types of aquarium filtration?
  3. The two main types of aquarium water filters
  4. What type of aquarium filter is best for your fish tank?
  5. Should I buy an internal or external aquarium filter?
  6. Do you need to leave your aquarium filter on all the time?
  7. Shop the best aquarium filters at Pond Planet

Why do you need an aquarium filter?

Aquarium filters are the cornerstone of any fish tank’s ecosystem. They help maintain clean, healthy water by removing fish waste and uneaten food, ensuring a habitable environment for fish. They also oxygenate the water in your fish tank, which is essential for fish survival.

By removing fish waste and debris, aquarium filters also remove harmful toxins such as ammonia and nitrate, which naturally build up in your tank water over time. These toxins become deadly to fish and other aquatic life if left untreated, so a filtration system is essential for fishkeeping.

What are the three main types of aquarium filtration?

There are three main types of filtration systems: Mechanical, biological, and chemical. While these systems work differently, they are each essential to keeping tank water safe for fish. 

Moreover, some aquarium filters are better at specific filtration methods, so understanding how these methods work is essential to creating a safe environment for aquatic life. Read on to learn more about each one!

Mechanical Filtration

Mechanical filtration removes large, solid waste particles from your aquarium, including uneaten fish food and excretion. Aquarium sponges and filter pads physically strain debris from the tank water, which you must manually clean from the filter media. 

Biological Filtration 

Biological filtration uses beneficial bacteria to remove harmful toxins from tank water, including ammonia and nitrate. Ammonia and nitrite naturally compound over time as a result of fish waste. If left untreated, they become deadly to fish, making biological filtration one of the most important types of filtration. 

This filtration style uses beneficial bacteria and aquarium plants to convert harmful toxins like ammonia into nitrite, and then into nitrate. This can then be removed through chemical filtration and regular water changes.

Chemical Filtration

Chemical filtration removes waste that human eyes cannot see: the waste that has dissolved into the tank’s water. This can be a range of things, from nitrate to chlorine and other impurities. It helps to prevent discoloured water and keeps those unwanted odours at bay.

The two main types of aquarium water filters

Aquarium filters are split into two categories: Internal and external filters. Read on to learn more about each type, including which might be best for your fish tank.

What are aquarium internal filters?

Aquarium internal filters are best for small to medium-sized aquariums and are designed to sit inside your fish tank, usually in the corner just below the water’s surface. 

How do internal aquarium filters work?

A water pump sits above the filter media, which includes a sponge. Water is drawn up through the bottom of the filter and the sponge, entrapping debris and tank waste. The bacteria in the sponge then converts harmful substances like ammonia into nitrite, clearing the water from harmful chemicals that will harm its inhabitants.

Oase BioPlus 200 Internal Aquarium Filter

What are external filters?

As the name suggests, external filters sit outside your fish tank, normally in the cabinet below. Water is pulled into the filter to be cleaned before being pumped back into the aquarium. 

How do external aquarium filters work?

External filters are great for larger aquariums, especially those with more demanding aquarium life. They work by drawing water out of the aquarium into the filter canister, where the water is then cycled through a series of different filters before being returned to the tank.

Due to their size, power, and special media, external filters can clean much more out of your tank, meaning you won’t need to clean the filter out as often as with a smaller internal filter.

Oase BioMaster 850 External Aquarium Filter

What type of filter is best for your fish tank?

Choosing the best aquarium filter for your fish tank can be overwhelming, as various filter styles are available. Below, we’ve covered the four things you should consider when choosing the right one for you.

  1. What is the size of your tank?

Different-sized tanks require different levels of filtration, so it’s important to choose a tank filter that can handle the requirements of your tank, including your aquarium size and the number of fish you have.

Generally, the water in your tank should be able to get through your aquarium filter at least four times an hour. If you’re teetering between two sizes, always go higher! For example, if you have a 100L aquarium, you should look at filters that can process 400LPH, like the Fluval Underwater internal filter.

  1. What type of fish and tank do you have?

The type of fish you choose affects the type of filter you need. For example, slower-moving fish cannot handle a constant filter flow and need a calmer, less aggressive form of filtration. With this in mind, researching your fish breeds before investing in a filter is essential, as it needs to understand and match their needs.

Similarly, you also need to consider your fish tank. For example, if you have a planted aquarium, a too-powerful filter can create too much current, preventing your plants from rooting.

  1. What is your budget?

There are aquarium filters to suit various budgets, so the great news is that you can easily find one to suit you. However, you must also consider how much you are willing to spend on your aquarium, fish and plant needs. It can be easy to fall into wanting the most expensive filter. However,  what’s good for one tank isn’t always good for another!

  1. How much maintenance work do you want to do?

The final thing to consider is what level of regular work you can dedicate to your tank. Any aquarium water filter you choose will need maintenance to ensure it works properly and performs its best. However, some require more maintenance than others.

Internal filters are relatively high maintenance, whereas external filters are much easier to maintain, requiring less cleaning.

Should I buy an internal or external aquarium filter?

The best filter type for you depends on your specific needs. Aquarium internal filters are generally easy to install and suitable for smaller tanks with fewer fish. However, they can take up valuable space in your fish tank.

If you have the space and budget, external filters are an excellent choice for fish tanks, especially if you have a larger tank with a large fish community. They are designed to provide high filtration and water movement levels and can easily be enhanced or maintained with aquarium filter media

Do you need to leave your aquarium filter on all the time?

You should always leave your aquarium filter running to maintain a healthy, oxygenated environment for your fish. If turned off, your tank water can experience a build-up of harmful toxins like ammonia and nitrate, which can be deadly to aquatic life.

Shop aquarium filters at Pond Planet

Aquarium filters are essential to maintaining a habitable environment for fish and aquatic life. They are responsible for cleaning the tank water and removing dirt, debris and fish waste which can be deadly to fish if left untreated.

At Pond Planet, we have a fantastic range of aquarium filters to suit every aquarium setup. So, whether you’re searching for a powerful external filter for a large fish tank or a small aquarium filter for a beginner fish tank, you can easily find one to meet your needs.

Explore our collection today to find the perfect aquarium filter for your tank, including internal and external filters by leading brands like Oase, Aqua One, and Fluval!

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