What Is an Undergravel Filter?

An undergravel filter is used in an aquarium to draw water through gravel as the primary filter media. It does this by keeping the gravel off the aquarium floor, and uses lift tubes to deliver clean water to the tank.

  1. How it Works

    • To help move the water through an undergravel filter, you should use either an air pump or a power head. Both move water through the lift tube and then through the gravel, where it is cleaned and put back into the tank.

    Primary Use

    • Along with keeping an aquarium clean, the primary use of a undergravel filter is to provide biological filtration.

    Is it Dangerous?

    • Sometimes undergravel filters come with a carbon cartridge. This is not necessary and can be dangerous, allowing toxins into your tank. Carbon cartridges may also restrict water flow through the aquarium.

    Maintenance

    • Undergravel filters have no filter media that need to be replaced on a regular basis, but cleaning the gravel regularly is a must and can be done with a gravel vacuum.

    Cost

    • Undergravel filters can cost between six dollars and thirty-four dollars, depending on how big your aquarium is and how much water it holds.