Filters – Vacuum cleaner of your aquarium

By reefspecialty, June 7, 2016

             Filter is one of the most essential equipment to consider while setting up an aquarium. For all aquarium species irrespective of their habitat, filters are compulsory to keep the aquarium’s water quality clean. Filters grab the physical substances and dirt that messes the aquarium. It can be anything such as the leftover food, excretes of the aquarium species, floating dirt or minute plant remains. By doing this, filters play a big role in the maintenance of the soul of an aquarium. A good filter will prolong the aquarium’s water quality and will minimize the cleaning effort.


In this article, let us first learn about the filtration types followed by the different types of filters.

Filtration Types

In general, three types of filtration are required to retain cleanliness and quality of aquarium water. They are:

  • Mechanical Filtration:

    This is the process of filtering the elements floating in the water. They can remove any suspending lumps in the water thus making the water look clear. During this process water in the tank runs through a foam or a spongy type of material where all the remains or bits from the water will be filtered out.

  • Chemical Filtration:

    This filtration is to remove any toxic chemicals or odor from the aquarium water. They remove the harmful unseen chemicals from the water in turn helping in maintaining a good water quality. You need to change your water every week if chemical filtration does not happen in your tank. During this process, water flows through activated carbon that filters out the ammonia, phosphate dissolved in the water.

  • Biological Filtration:

    Helps in maintaining nitrogen cycle by converting ammonia into nitrates. Fish excretes and left over food will increase ammonia level in aquarium water. This is very harmful to the fishes. A colony of beneficial bacteria produced during biological filtration will do this activity. Therefore, a biological filtration helps in reducing the ammonia by converting them into nitrate.

A good filter should do all these three types of filtration in your aquarium irrespective of the size or species in the aquarium.

Filter types & their uses

Today there are many kinds of filters available in the market. Filters differ based on their work mechanism, design and filtration techniques used. Let us analyze the common filters used by the hobbyists.

Sponge filters

Sponge filters are very efficient for small volume tanks. They produce less current and hence veryfilter1 gentle. They do not suck fish fry and is available at a reasonable price. They provide all three filtrations like mechanical, chemical and biological filtration. As the name implies water passes through sponges, which builds up a large colony of beneficial bacteria in a course of time. These bacteria make the filtration process more efficient. Hence, do not use tap water to clean these sponges; Use the water from the aquarium to clean these sponges, so that we do not kill all the beneficiary bacteria. Breeder filter or air driven filters are the other names of sponge filters. It is best suited for hatcheries, maternity tanks, nursery tank and fry tanks. They are not advisable for an aquarium with live plants.

Power filters

 These filters have a water pump that pulls water in and out of the tank and into a box that hangs on filter2the tank’s rim. Gravity helps in pulling the water back into the tank. Water passes through the filter pads proving mechanical filtration. Power filters removes toxin and chemicals from the water, when water passes through the filter’s carbon thus providing a chemical filtration. They have an easy and simple maintenance replaceable cartridge that acts as a biological filtration. A large quantity of beneficiary bacteria forms inside these cartridges. The design is in such a way that they hang off on the back of your aquarium. Hence, known as hang on back filters. It is the most commonly used aquarium filters by hobbyist due to their maintenance feasibility. Cartridges inside these types of filters need to be replaced once in 4 weeks to provide efficient filtration.

Under gravel filters

As the name implies, these filters are placed under the aquarium gravels. Tank water is pulled through the gravel and uplift tubes. Mechanical filtration occurs while water passes through the gravel and the biological filtration is limited from the water passing through the substrate. Clean this substrate properly and periodically; else, they will increase the level of hydrogen sulfide, as the substrate will have leftovers build on them. Under gravel, filters design are not compatible to do chemical filtration, which is the biggest drawback of under gravel filters. Best filters for goldfish aquarium, however not the best choice for an aquarium with many live plants.

Canister filters

Excellent filters for larger tank with amazing work mechanism. These filters can be customized according to our needs. Therefore, we can configure biological, chemical and mechanical filtration as per our requirement. During filtration, water is sent back into the tank through a spray bar that helps in reducing water evaporation and current. The floss pad inside the filter removes fine particulate materials. It can filter out a large quantity of water quickly, hence best suited for large aquariums. Canister filters are the best choice for an aquarium with cichlid and live plants.

Internal Filters


Commonly used filters by small aquarium holders and mostly placed at the bottom of the tank. They are very compatible and occupy less space. Best suited for Nano or aquarium under 20 gallon. This filter sucks up the dirt using their suction cup. At times, they require an air pump and airline connected to it to produce the water movement up through the filter. The air bubbles then disperse to the top of the surface making good mechanical, chemical and biological filtration.

Wet / Dry filters or Trickle Filters

Hobbyist rarely uses it, as it requires a lot of effort to setup. However, these extra efforts are for no loss as they provide a very efficient biological filtration. It is best suited for salt-water aquariums. The filter design is in such a way that it exposes to a little amount of air as well as to the aquarium water providing a great biological filtration, because of this it is called wet/dry filters. Their design is very proficient that helps in the growth of numerous bacteria that in turn helps in processing the waste material efficiently. Chemical filtration occurs when the water flows through the chemical media. However, Mechanical filtration is inadequate, as water has to pass through large-pored sponges. They are best suited for both saltwater and fresh water aquarium. The sponges and pre –filter in these types of filter should be washed twice a month.

Fluidized Bed Filters

  This type of filters are designed with a pump to create water flow, a small box that  contains a media like sand, white quartz or a sintered glass and an outlet to push back the purified water into the tank. You will require space outside the tank to fit these filters. Clean and wash the pump and media frequently, for efficient working. As the box, containing the media will have enormous beneficiary bacteria proper care is required while cleaning them. They are best suited for fresh water aquariums.

Basic Filter Maintenance tips






  • Make sure to keep the water level one inch from the lip of the filter
  • Clean your filter’s physical parts every 3-4 weeks with normal tap water
  • Make sure to clean the sponges inside the filter with the water from the tank so that the good bacteria are not killed
  • Disconnect the filter from the socket and take it out of the tank to do an efficient cleaning
  • It is good to change the Filter inserts like floss, Algone, activated carbon at least every 6 weeks
  • Choose a filter that is capable of supporting tanks large than your aquarium size for efficient filtration





  • Do not clean the filter crystal clear, as it will kill all the beneficiary bacteria
  • Do not use liquid soap or any cleaners to clean the filters
  • Do not use any hard equipment’s even the fingernails, as it would damage the electrical or delicate parts of the filter

The Bottom Line

Filters are the soul of your loving aquarium. So be very careful in choosing one. Make sure to consider the tank size, the type of fishes and their habitat into consideration before buying a filter. Filters are the main equipment to maintain cleanliness and water quality of an aquarium. In addition, be extra cautious while cleaning a filter than a fish tank; make sure neither to damage the mechanical part nor to use any tool that damages the filter. A good filter reduces the aquarium maintenance effort also. Therefore, it is necessary to choose the right filter than blindly picking a high efficient expensive filter.

Algae - Boon or Curse to your aquarium?
Stop Believing Myths! – Fish keeping & Aquarium care

What do you think?

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>

  • Search

  • Subscribe to our Newsletter

  • Information

    Phone Hours
    M-S 10am-7pm CST
    Sunday 11am-6pm
    (435) 671-6522
    1465 E. Southlake Blvd
    Suite 601
    Southlake, Texas 76092
    **We are next to Nordstrom Rack**