Proper Under-Gravel Filter Installation

An under-gravel filter for your freshwater aquarium is economical, effective and easy to set up and maintain. It provides plenty of cleaning power for most small to medium installations through biological and mechanical filtration and you never need to clean it directly.

  1. Evaluate Your Needs

    • A 30-gallon tank stocked with African or South American Ciclyds is a prime candidate for under-gravel filtration. Stock that same 30-gallon tank instead with goldfish--big eaters and waste producers--and you'll have greater filtration needs: an added supplemental filter or a different system entirely. Discuss your ideas with the staff at the aquarium store and find out if your tank as planned will work with under-gravel filtration. If cost is an issue, modify your plan so that an under-gravel filter is appropriate.

    Assemble the Filter

    • An under-gravel filter is the first thing to go in when you set up the aquarium. They are made up of several plates, the filter, riser tubes and a pump. Assemble the plates in the bottom of the tank. The plates must abut completely and securely for the filter to work. If you are using only one riser tube, attach it to the port in the plate and cover any other ports with the caps that came with your filter. If you are using more than one riser tube (you have two or more pumps), attach those and close any remaining open ports. Fit the pumps to the top of the tube.

    Adding the Gravel

    • Rinse the gravel thoroughly before you add it to the tank. There is a lot of dust on gravel, and you want to begin with as little cloud in the water as possible. Spread it evenly over the filter without too many dips or pockets.

    Maintenance

    • Under-gravel filters don̵7;t need to be cleaned. The bacteria bed will grow in the filter media and provide the biological filtration. Solid waste will collect on top of the filter or in the gravel itself. Water changes of the size and frequency that are recommended for your setup should always be accompanied by thorough gravel vacuuming, but again, don̵7;t clean the filter itself or you will lose the important bacteria.