7 Types of Aquarium Filters You Should Know

There are many types of aquarium filters on the market today. Each one has a designated design for one’s preference.

There are some basics that we need to learn about first such as the size of the aquarium versus the filter size and type along with the three types of filtration that occur in an aquarium.

The three types are mechanical, chemical, and biological filtration.

  • Mechanical filtration is where water is forced through filter media which is designed to catch particles suspended in the water in your aquarium.
  • Chemical filtration occurs when toxic chemicals pass through a resin or media. Some chemical filtration products target specific excessive nutrients or chemicals from the aquarium.
  • Biological filtration is the breakdown of different bacteria. This is called the nitrogen cycle where waste products, food, and fungi are broken down and create ammonia. Ammonia is toxic to the aquarium’s inhabitants. If there is sufficient space for the beneficial bacteria to grow, your nitrogen cycle will work properly. A biological filter is designated by the amount of space made for the bacteria to grow on.

Now that you know the three types of filtration in an aquatic ecosystem, let’s take a look at the different types of aquarium filters.

Sponge/Air Driven Filter

The most basic setup filter that does not do much in the way of mechanical, chemical, or biological filtration is the Sponge/air filter. These are made mostly for breeding, fry (baby fish) in nursery tanks, hospital tanks, and aquariums with small fish or invertebrates.

AQQA Aquarium Sponge Filter, Power Driven Double Biochemical Water Filter, Quiet Submersible Foam Filter with 2 Extra Sponges, 1 Bag of Filtered Ceramic Balls for Fresh and Salt Water Fish Tank (S)
The AQQA Aquarium Sponge Filter

A sponge filter is powered by an air pump where water is forced to pull through the sponge-like material. The sponge is capable of producing biological and mechanical filtration because beneficial bacteria live on the sponge.

You then use aquarium water to clean the sponge to be careful not to kill the beneficial bacteria.

These can vary in price from $5.00 to $40.00.

Hang On Back/Power Filters

The most common style filters for hobbyists are the hang on back style filter. The reason they are common is because they provide excellent mechanical, chemical and biological filtration.

AquaClear 50 Power Filter, Fish Tank Filter for 20- to 50-Gallon Aquariums
The AquaClear HOB filter

They hang over the back (or side) of your aquarium and suck water up through their siphon tube.

Mechanical filtration comes from water passing through a filter pad or floss, next chemical filtration occurs from water flowing through carbon which removes toxins or chemicals from the water.

Lastly, biological filtration happens inside the filter cartridge. A large number of beneficial bacteria form within the filter cartridge and this is what causes the biological filtration and is limited to the amount of oxygen within the aquarium.

Most new systems have bio wheels or biological filter pads. Bio wheels are wheels that have a biological filter on them and water passes over them creating a great biological filter.

These can vary in price from $10.00 to $150.00.

Canister Filters

Canister filters are among the popular styles of filters used by hobbyists. These are especially great for aquariums 40 gallons or larger.

SunSun Sun HW-704B 525 GPH 5-Stage External Canister Filter with 9W Uv Sterilizer
The SunSun Canister Filter

Canister filters provide excellent mechanical, chemical, and biological filtration due to their size which is significantly larger than most hang-on-back filters.

These have a siphon tube and flexible pipework going to the filter and then a pipe back up and into the tank with a return “water bar” that spreads the water outflow through a long bar.

Canister filters are great for a cichlid tank, saltwater, or planted aquariums.

Canister filters are pressurized which makes mechanical filtration even better by forcing the water through fine material that can trap smaller particles.

Chemical filtration is done the same way and thus makes it a better chemical filter.

Biological filtration is based on oxygen present in the water going through it. Since there is no air-to-water contact, biological filtration is not as sufficient in these types of filters.

These filters can range in price from $90.00 to $500.00.

Undergravel Filters

The filters are placed under the gravel and pull the water through the gravel/substrate and up tubes called uplift tubes.

Lee's 50/65 Premium Undergravel Filter, 18-Inch by 36-Inch
Lee’s is one of the most popular brands of undergravel filters

There are two ways you can get water to come up these tubes. That is by an airstone and air pump or a power head that fits onto the top of the uplift tubes and pumps the water across the top of the aquarium.

Mechanical filtration occurs as water passes through the gravel but the downside is that biological filtration is limited by the water passing through the substrate.

Unfortunately, chemical filtration does not happen with an under gravel filter. Also, make sure you agitate your substrate and clean it or there will be detritus buildups and this will cause high levels of hydrogen sulfide.

These range in price from $8.00 to $60.00.

Internal Filters

Internal filters are compact which makes them great for small and nano aquariums.

NICREW Aquarium Internal Filter, Submersible Power Filter with Multiple Function, Aeration System with Sponge Filter for Fish Tanks 5-10 Gallon, 53 GPH, 5W
NICREW Aquarium Internal Filter

Most people use these in aquariums under 20 gallons as they use suction cups and stick to the side of the aquarium glass.

Most hobbyists place these at the bottom of their aquarium so dirt has no time to settle before getting sucked up into the filter.

Some internal filters also require an air pump and airline connected to it to produce the water movement up through the filter. The air bubbles then dissipate to the top of the surface making good mechanical, chemical, and biological filtration.

The price of this style filter ranges from $8.00 to $30.00.


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