Are you setting up a new fish tank? You’ll need a filter to help keep the water clear, and clean, and the fish healthy. Keep reading to learn more about the many types of aquarium filters. 

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What Is An Aquarium Filter?

In a nutshell, an aquarium filter helps to keep the water and your fish tank as clean as possible. It allows you not to worry about cleaning the tank daily. Instead, you can let the filter do the work.

How does a filter keep the water clean? Through biological, chemical, and mechanical means.

These three types of filtration break down and get rid of the following in your aquarium:

  • Dangerous chemicals and metals (from tap water)
  • Decaying organic matter
  • Excess fish food
  • Fish waste
  • Floating particles

If these aren’t cleaned or filtered out of the water, it can harm your fish. For instance, they could get sick and possibly die.

So, do you need a filter for your fish tank? Yes, you do. Filters keep the water clean and your fish safe and healthy. Also, it’s less cleaning for you. 

But did you know there are many different types of aquarium filters? Each has pros and cons, so it’s up to you to research and determine which filter is the best for your aquarium.

Before we get into that, let’s go over the types of filtration these filters may provide.

long fish tank with many plants in the water

Biological Filtration

Not all bacteria are harmful. Harmless bacteria can grow on any surface inside your fish tank. For example, it’ll stick to the gravel, the walls, and decor you have inside.

Your fish’s waste creates ammonia and nitrogen compounds, which are harmful. Biological filtration (along with any live plants you may have in the water) uses beneficial bacteria to consume these toxins.

Overall, biological filtration makes the water safer for your fish community.

Chemical Filtration

Chemical filtration removes unwanted impurities from the water. These impurities may include medications or tannins.

Overall, chemical filtration helps keep unwanted debris out of the water, so it’s safe for your fish.

Mechanical Filtration

Finally, mechanical filtration acts as a garbage can. Like a coffee filter, it filters through any harmful things in the water, leaving clear water. It filters fish waste, excess food, and more.

When the mechanical filtration (often looking like a sponge) is full or dirty, you need to clean it, just like taking out the trash when the can gets full.

In a nutshell, mechanical filtration helps keep your water clear.

Now that we know what the 3 types of aquarium filtration are and what they do, which filter would best suit your tank?

Types Of Aquarium Filters

When you plan on getting an aquarium, one of the first things you’ll need is a fish tank and filter. Of course, you’ll want to get this up and running before you bring home your fish.

So, one of your first decisions will be, “what type of filter do I need?”

Let’s go over the many options.

fish tank filter lying on its side on a white backdrop

Canister Filter

Also known as external filters, these massive filters are great for tanks between ten gallons and 400 gallons in size.

The filter media capacity is large, properly keeping the aquarium in a thriving environment. Setup and cleaning are easy too.

However, canister filters are most often used by more advanced fish keepers. Also, they can be pricey.

Shop canister filters.

Diatomic Filter

Diatomic filters are primarily used in special situations. They act as a one-time use (since the media needs to be changed after every ues) to get fine particles out of the water. These fine particles, such as diatomic algae, are so small that other filters may miss them.

Sometimes, diatomic filters are included in other filters. However, they can be pricey if you buy a diatomic filter on its own.

Shop diatomic filters.

Fluidized Bed Filter

If you need a biological boost, then this type of filter is great. It will work well with fish tanks between 20 and 40 gallons and in addition to another filter.

However, it’s not customizable to add chemical or mechanical filtration systems. It’s also tall, so you’ll need a tall tank rather than a wide one.

Shop fluidized bed filters.

Hang-On-Back (HOB) Filter

This type of filter is as it sounds: it hangs on the back of your aquarium. You may also know this filter type as a power filter.

These come in varying sizes but may be best suited for smaller setups. Also, you can use it for both saltwater fish tanks and freshwater aquariums.

HOB filters are cheap at the pet store and are easy to set up. However, they do take quite a bit of maintenance. Also, if you’re looking for a quiet filter, HOB filters can get loud, especially when the water levels get low in the tank.

Shop HOB filters.

fish tank filter inside the aquarium with many plants

Internal Aquarium Filter

These types of filters are often included with tank start-up kits if you’re buying your first aquarium. You may also know them as box filters, corner filters, or internal power filters.

Internal filters are small but mighty. They’re also cheap to buy and easy to run.

However, they’re not powerful enough to properly clean a saltwater aquarium. So, this filter is best suited for freshwater fish tanks only.

Shop internal filters.

Live Plants

Believe it or not, you don’t need equipment for proper biological filtration. If you’re familiar with the nitrogen cycle, live plants act as a natural biological filter.

However, live plants do not add any mechanical or chemical filtration. So, you’ll either need to add a separate filter in addition to the live plants or clean your tank more often.

The plants will also make the tank look nicer aesthetically! 

Shop live plants.

Protein Skimmer

A protein skimmer is a great option if you have a saltwater aquarium. However, it’s an addition to another filter, not a filter on its own. Also, it cannot be used for a freshwater fish tank. 

Protein skimmers are more powerful than surface skimmers since they skim the entire tank. They do a great job and are good additions to another filter. However, protein skimmers can be pricey.

Shop protein skimmers.

sponge filter for fish tank on a white backdrop

Sponge Filter

Sponge filters are our personal favorite to use for an aquarium. They’re low cost, don’t take up much space in the tank, are quiet, and are simple to maintain.

These filters require an air pump and tubing so that setup might be a learning curve. Once it’s running, you won’t need to worry about cleaning it for a few months unless it’s super dirty.

The water flow is gentle but creates surface tension allowing oxygen to go through the tank. Also, they come in many sizes so that they can be used with any fish.

Shop sponge filters.

Surface Skimmer

While surface skimmers aren’t a full filtration system, they’re a great addition to any tank. This product skims the water’s surface, filtering through floating debris, oil, algae, and anything else floating on the top.

You’ll need a separate filter, such as a canister filter, to ensure the tank is properly cleaned. However, surface skimmers can keep the surface clear, thus helping the other filter. 

Shop surface skimmers.

Sump Filter

If you’re a hard-core, expert aquarium hobbyist, then sump filters are an excellent option. This filter acts as a separate tank, but it’s a large filter.

You can put the sump filter under the main aquarium or behind it, so it doesn’t get in the way of the aesthetics.

They work well for saltwater and freshwater tanks and are customizable. You can build it however you want and make it do what you need. Extra equipment, such as a tank heater, can also be added to the sump filter.

However, they can be costly and take up a lot of space.

Shop sump filters.

two goldfish swimming at the bottom of the tank with red and white gravel

Under Gravel Filter (UGF)

This filter is another that does exactly what the name suggests. This filter rest at the bottom of the tank, underneath the gravel. The water gets sucked into the bottom to go through the filtration system.

However, these filters have had issues. They may not circulate well, often making the water look cloudy. They’re a great biological filtration system, though.

Also, these filters can only work with gravel. More fish keepers use sand as substrate, which is incompatible with a UGF. The sand will get sucked into the filter and clog it. 

Shop UGF.

Wet/Dry Filter

Also known as trickle filters, these products aren’t necessarily filters on their own. Wet/dry systems are made to go inside sump systems. They add extra biological filtration to the sump and act as a pre-filter before the water goes through the rest of the sump filter.

Shop wet/dry filters.

Question Corner: FAQs About The Types Of Aquarium Filters

If you have further questions, you can read through the frequently asked questions below about fish tank filters.

How Often Should The Filter Be Cleaned?

Most filters need to be cleaned at least once a month. You won’t always need to change the media, but a good rinse in tank water will do the trick. However, it’s a good idea to check the filter at least once a week to ensure it’s working properly and not clogged.

saltwater fish tank with many coral, rocks, fish, and sand

How Often Should The Filter Run?

No matter what type of filter you have, it should run for 24 hours a day, seven days a week. Not only do the filters keep the tank clean, but it produces water flow, which your fish need to thrive.

Is A Filter Needed For Small Tanks?

If you have fish inside a tank, no matter how small, then yes, you need a filter. The filter keeps the water clean, provides water flow, and oxygen to the tank to keep your fish happy and healthy.

What’s Inside A Fish Tank Filter?

Filters typically contain filter floss, filter sponge, activated carbon, bio balls, or media rings. Depending on the type of filter you have, not all of these will be included. You might be able to add it yourself or not. 

Which Aquarium Filter Is The Best?

Whichever filter you decide upon will depend on your tank’s environment. Is it freshwater or saltwater? What species of fish do you plan to keep? Research your tank’s needs, cost, and ease of use to effectively decide.

empty fish tank with water, gravel, and a plant with text centered reading 12 Types of Aquarium Filters You Need To Consider |
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