How To Select The Best Aquarium Filter

Last updated October 2018

Choosing the best aquarium filter is vitally important. This is an essential piece of equipment that keeps the tank water clean by removing impurities and in turn keeps your fish healthy.


There’s plenty of options and the best aquarium filter for you depends entirely on the type and size tank you have, whether you’re breeding fish, if you’ve got a problem with algae blooms in your tank that just won’t shift or you have a large saltwater aquarium.

7 Fish Tank Filter Systems

Some filters perform specific functions and are better suited to specific conditions.


There’s also a huge variation in price. We’ve summarized filter types and highlighted their ‘best for’ use so you can find the best for your situation.

How do Fish Tank Filters Function?

They perform one or more of the functions of filtration.

The chemical filtration process involves the removal of toxins, dissolved matter, ammonia and odor from the tank water. The chemical filtration system may not always be necessary.

Mechanical filtration removes heavy waste and sediments.

Biological filtration is crucial for beneficial bacteria and to separate toxins and decay from the water.

#1 Power Filters

best filter for 55 gallon aquarium

Power filters are very effective, commonly used and in fact the most popular external aquarium filters.


External filters come in a range of sizes to suit small to mid range sized tanks and handle mechanical as well as chemical filtration and bio filtration. Pricing is inexpensive.

Power filters are easy to install and maintain.


As a guide, we’ve chosen the popular Aqua Clear Power Filter here as one of the best aquarium filters based on effectiveness, price and reputation.


It offers 3 levels of filtration, mechanical, chemical and biological. The components within the filter responsible for the different filtration services need to be replaced on a regular basis.


These are the guidelines.

AquaClear foam filter insert– replace every 2 months

AquaClear activated carbon filter insert – replace every month

AquaClear biomax filter insert– replace every 3 months


Cleaning the fish tank filter is easy, but do this job regularly. We recommend every 2 weeks to keep it working at its best.

The cleaning procedure is very simple.

1. Unplug and separate the components

2. Thorough rinse and remove any build up of deposits in all components including cover and filter basket.

3. Reassemble the filter and attach to the back of fish tank.

4.Fill with aquarium water

5. Plug in and it will start up working again within a few seconds

These are the components that need to be replaced regularly. They’re cheap to buy and keep the filter running efficiently

best fish tank filter

external filter for fish tank




best 10 gallon aquarium filter

  • Choose me for small to medium sized fish tanks

#2 Canister Filters

best canister filter
freshwater canister filter

These are heavy-duty and more powerful external aquarium filters best suited to medium and large tanks.


Suitable for freshwater, saltwater, reef and turtle tanks.

With canister filters water is forced through a filter medium. Their biological filtration capacity can also be increased with a bio-wheel.


They are more difficult to clean and maintain then power filters.


There is a step up in price which reflects the fact that this is a more powerful system for larger tanks.


best aquarium canister filter

  • Choose me for a powerful external filter for a large tank

#3 Diatomic Filters

what to use to kill algae in fish tank

diatom for a saltwater aquarium

If you’re battling with green water in your tank due to recurring algae bloom problems this is a filter system for you.


Diatomic aquarium filters are submersible units that clean the water by getting rid of even very small particles. They’re suitable where fine particles like diatomic algae cause a problem.


This UV radiation filtration system safely eliminates cloudiness, impurities & bacteria. The growth of mold, yeast and other pathogens is stopped by the UV sterilizer. The result is clear water in which your fish can thrive.

  • Pick me if your looking for the best filter to battle algae blooms and eliminate cloudy water

#4 Sponge Filters

sponge filter for betta tank

Size options available

  • up to 10 gallons
  • up to 15 gallons
  • up to 20 gallons
  • up to 35 gallons

These are most suitable for fish tanks with fry and tiny fish as they are gentle and produce minimal current. There’s reduced risk of drawing the fish or delicate fish like bettas being injured through the filter operation.


The filter still produces tiny bubbles increasing oxygen in the water. Sponge filters manage biological as well as mechanical filtration.


The sponge draws bacteria and helps to break down harmful waste (ammonia and nitrite).

They quickly clog with excess debris and need frequent cleaning.

Biochemical sponge filters can also be used as a secondary filter to the main filter. They are cheap to buy.

  • Pick me for a sponge filter for a betta tank or filter for fry tanks

#5 Fluidized Bed Filters

a fluidized bed filter for saltwater reef aquariums

size of a fluidized filter


These filters are highly efficient chemical filters using sand or media of your choice to promote uniform water flow.


Fluidized filters are suitable for all aquarium sizes.


You can make a fluidized filter quite easily. The product here is a base and you’ll need to buy a pump and tubing separately

  • Perfect for use in reef aquariums

#6 Wet Dry Trickle Filters

trickle filter for freshwater or saltwater tanks

These filters expose water to air by allowing the water to dribble over the media which can include strands, plastic balls, or floss.


Improve the efficiency of an installed biological filtration system and mechanical system by installing a wet dry trickle filter.

They can clog easily. Measures to reduce this problem include installing a pre-mechanical filtration system. Also incorporating a good pump will cut down on your maintenance.


Wet dry filters are suitable for saltwater tanks and highly recommended for an aquatic eco-system.

*Also suitable for freshwater aquariums up to 120 gallons.

  • Pick me to use in a large aquatic eco system

#7 Under Gravel Filter or UGF