Fish Tank Filter Types

Aquarium filters are extremely important for the health of your fish tank. While there are many types of filters for different purposes, all filters require regular cleaning for optimal performance. However, the cheaper, less effective filters will require more maintenance. Consider the size of your tank, your budget and how much time you can dedicate to cleaning your tank and filter when purchasing a filter.

  1. Power Filters

    • Power filters are commonly used in fish tanks. They are plastic containers that hang on the side of the aquarium and contain all necessary components for an effective filter. The filter media, typically foam, provides mechanical and biological filtration. Mechanical filtration removes debris within the water and biological filtration grows healthy bacteria, called ̶0;beneficial bacteria,̶1; that are necessary to maintain proper water chemistry.

      Mechanical filters use chemical-filtration cartridges that are easy to remove and replace. Chemical filtration is a chemical or resin, typically activated carbon, which removes toxic chemicals from the water. The pump is built into the container and pulls water through the filter media and releases it back into the water. Power filters cost between $9 and $90 and are ideal for tanks under 55 gallons.

    Corner Box Filters

    • Corner-box filters are small plastic boxes filled with filter media that are installed directly into the aquarium. An air pump forces water into the box and through the filter media, then returns the water to the aquarium. While corner-box filters are cheap, ranging from $15 to $45, they have low efficiency and are not recommended for large fish tanks. A box filter will work well for 10-gallon tanks.

    Under Gravel Filters

    • An under-gravel filter looks like a plastic grate and is installed under the aquarium substrate. Water is forced through the gravel with a water or air pump. The gravel helps catch moving debris and acts as a mechanical filter. It also serves as a biological filter by growing beneficial bacteria. Some under-gravel filters have chemical-filtration attachments. Many aquarists choose not to use under-gravel filters due to their inefficiency at removing debris, which can result in high levels of nitrate and phosphate, and at growing beneficial bacteria. These filters can also develop stagnant patches and release harmful hydrogen-sulfide gas. Weekly gravel cleaning and partial water changes are necessary. Use a second filter if using an under-gravel filter. Under-gravel filters cost between $15 and $80 and can be used in any size aquarium.

    Canister Filters

    • Canister filters are external fish-tank filters and are normally placed below the tank. The canister filter is pressurized, forcing water through the filter media. This type of filter has highly efficient biological-, mechanical- and chemical-filtration abilities and can be used to filter large aquariums from 30 gallons to 400 gallons. Canister filter cost between $100 and $450.

    Wet/Dry Filters

    • Wet/dry filters are external filters that work by siphoning water out of the aquarium and into the filter container, then returning the water with a pump. Wet/dry filters expose the water and filter media to oxygen. This promotes beneficial-bacteria growth, making wet/dry filters the most effective for biological filtration. These filters also contain mechanical filtration and chemical filtration. They are made from large containers, such as old fish tanks, and work well for large stocks of fish. These filters can be custom made to fit any size aquarium, from 10-gallon tanks to 400-gallon aquariums and larger. A wet/dry filter will cost between $160 and $450.