Aquarium Filters and Pumps Buying Guide

Aquarium filters and pumps help to keep your water clean and in optimum living conditions for your pet fish .  While pumps circulate the water and provide more oxygen, filters actually remove toxic materials.  Both devices not only help to keep fish happy, but they also work to maintain a vibrant looking tank  with clear water and healthy plants .  The key is knowing which varieties will work best for your aquarium size as well as for the particular breed and number of fish you own.

Internal Versus External Filters

Most new aquariums come already fitted with an internal filter .  But if you are wondering if an external filter might work better, consider this information:

  • External filters  have very powerful pumps. If your tank is small, you may prefer an internal filter or hang-on filter because they can be specially designed to handle small amounts of water.
  • The use of oversized external filters can work well for serious pollution problems, but they create powerful currents that may cause the fish to get sucked into the filter itself. These type of filters may also make the tank more prone to algae.
  • External filters are easier to clean.
  • If you have small children or pets that run the risk of knocking off the filter, it's best to stick with an internal one.
  • Big aquariums with low water levels--like frog or turtle tanks --work best with external filters.

Biological, Chemical and Mechanical Filters

  • A biological filter  is made up of living organisms (bacteria) that feed off the ammonia produced by waste in your tank.
    • There are two possible bacteria types that filters culture.  The first type breaks down the ammonia into nitrites, and the second type breaks down the nitrites into nitrates.
    • A sponge can be considered a type of biological filter that can be used in conjunction with a small internal mechanical filter to reduce pollution.
    • Sponge filters  come in a range of sizes to accommodate all tanks.
    • Sponges are good for baby fish because there is less chance that they will get sucked into the filter.
  • A mechanical filter  uses gravel or diatomaceous earth to trap unwanted particles floating in the water.
    • Many modern mechanical filters contain carbon to increase filtration.
  • Chemical filters  use different chemical substances to enhance filtration.
    • Carbon is the most common chemical used.

Other Filter Positions and Varieties

  • Box  or corner filters  are small, plastic containers that hold carbon and filter floss.  They are connected to an air pump to promote water circulation.
  • Under gravel filters  fit in the bottom of the aquarium under a few centimetres of gravel.  They connect to an air pump or power head to promote water circulation.
  • Power-head filters  come in a variety of sizes and shapes, suiting most small and medium tanks.  They are the most common filters and are stuck to the side or back of the tank to connect to a power source.  Power-head filters work by drawing water through the filter media--any material that catches debris and bacteria--and forcing it back through the tank.  
  • Canister .hang-on-back  (HOB) or fluidized bed filters  are large external filters that hang on the outside of the aquarium and have their own internal pump.  A sealed container inside traps water waste.
  • Sump filters are completely separate tanks--usually around 20 gallons--that are split into compartments for various uses.
  • Air box  or foam filters  stick to both sides of the tank or stand freely in the bottom of the tank.  They contain a foam material to help capture bacteria and filter out debris.

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