Aquarium Filter Types - Planted Tank Mates
Hang on back filter hanging on edge of aquarium glass

Aquarium Filter Types


There are so many types of aquarium filters on the market it can be confusing for a first time hobbyist.  Consider the size of your aquarium, livestock, and available space when making your selection.  Furthermore, each type of aquarium filter has specific maintenance requirements.  There are options that make routine maintenance a breeze, and others that require you to disassemble the set up.  This article is meant to explain a few basic types of filters, how they work and what to consider for your next, or first aquarium.

Filtration Methods

Before we jump into the various types of aquarium filters, we need to have some general understanding of basic filtration.  There are 3 combinations of filtration that can be applied: mechanical, biological and chemical.  All 3 serve to clean your aquarium because your contained ecosystem does not have the natural resources and water flow to do it by itself.

Mechanical Filtration

Mechanical filtration generally applies to sponges and floss pads.  They are the first part of any filter system and its meant to catch debris, loose leaves or solids that float around your tank.  You can buy specific ones that fit your model or larger sheets and cut them up to size.  Part of your routine maintenance would be to take these out and rinse them with your tank water.  Never rinse these sponges in foreign water such as the tap water from your sink.

Filter Sponge – available on Amazon
Biological Filtration

Biological filtration is essentially beneficial bacteria.  They grow on the bio rings, bio balls or on the mechanical sponges of your filter.  Emphasizing again why to never rinse your sponges in foreign water.  The same sponge from your mechanical filtration also serves as biological filtration.  Only rinse your sponge or bio media with the same tank water that contains the same bacteria.  These porous materials contain the beneficial bacteria that break down ammonia and nitrogen that can be harmful to livestock.   When it comes to biological filtration, the more surface area you have the better.  The larger the sponge or the more bio rings you have means a stronger and stable bacteria colony.


Bio Rings / Ceramic Rings – available on Amazon
Bio Balls – available on Amazon
Chemical Filtration

Chemical filtration refers to added media such as active carbon.  It helps keep the water clear, remove organic waste and bad odors.  There are 2 sides to its use as many would argue that it’s not needed if you have a healthy tank.  Some prefer to use it for tanks with large fish and a heavy bio load.  An alternative would be to temporarily use it to help with ammonia spikes or to clean added medication from your tank.

Activated Carbon – available on Amazon

Aquarium Filter Types

Sponge Filters

Sponge Filters are the simplest and most cost effective filter for any tank.  The sponge inside your tank serves both mechanical and biological filtration.  An air pump forces air bubbles into your sponge (air stones help reduce bubble size and noise).  When the bubble rises, it pulls water through the sponge and that’s when your filtration begin.  When the sponge is dirty, remove it and clean in a separate cup of the same tank water.  That’s it.  Easy maintenance, cost-effective and it tackles 2 types of filtration.  The negative side is its visibility and it will occupy space inside your aquarium.  You’ll also have to clean the sponge more frequently because it’s the only filtration system you have.

Sponge Filter -available on Amazon


aquarium air pump – available on Amazon
Hang on Back (HOB) Filters

HOB Filters have the advantage of staying outside your tank.  It literally hangs on the aquarium edge and has a stem that dips inside the water.  That stem is your filter inlet.  It sucks water from your aquarium into the filter, cleans it, and spits out clean water at the top.  Inside the HOB filter are various types of sponge and filter media.  A larger HOB filter provides the space advantage to customize all 3 types of filtration.  Cleaning is as simple as rinsing the sponges and media in a separate cup of the same tank water.  If your tank is against a wall, measure the space available for your HOB filter.  Also, it’s recommended to have a pre-filter sponge.  This is a small sponge at the inlet pipe which helps prevent livestock and solids from getting sucked in.  HOB filters can go on without cleaning a little longer than sponge filters, but that all depends on how dirty it gets.

HOB filter with pre-filter sponge at inflow pipe – available on Amazon
Canister Filters

Canister Filters are a little more complicated, yet popular for its versatility.  They can support mechanical, biological and chemical filtration, and you can include in-line attachments like water heaters and CO2 atomizers.  These units need a storage area under your tank.  The filter system itself has a chamber or basket for you to place all your filter media.  The unit is then connected by 2 hoses which cycles water in and out of your aquarium.  This is when you can use glass lily pipes, and that’s essentially all that occupies your tank.  Maintaining this can be a bit more time consuming.  You need to turn off the filter, disconnect the hoses and remove the media to rinse with the same tank water.  Using quick disconnects can help with a much faster and easier disassembly.  The good thing about canister filters is that it does not require as frequent cleaning as sponge and HOB.  If managed well, it can be done every few months rather than weeks.

Canister Filter setup – filters available on Amazon

All Things Considered

There are many more types of aquarium filters on the market, all that operate in a similar fashion.  Each aquarium filter type has its set of pros and cons which should be considered with the size of your tank and livestock.  Biological filtration is the most important one.  Be sure to provide as much surface area or media as possible and only rinse with the same tank water.  Mechanical filtration is next as it helps collect the solids and debris that would dirty your filters.  Chemical filtration has many great benefits and is optional, depending on your setup.

Always rinse filter media with the same tank water


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