How to Create an Undergravel Filter for a Fish Tank

Aquariums are a form of relaxation and therapy that have the potential to be costly depending upon the type of equipment and fish you include. However, using a homemade undergravel filter cuts cost and produces beneficial bacteria for the fish tank.

Things You'll Need

  • Plastic lid
  • Gutter screen
  • PVC pipe
  • Sand paper/sander
  • Stainless steel nails
  • Aquarium sealant
  • Gravel
  • Airstone
Show More

Instructions

    • 1

      Begin a plan for the undergravel filter by measuring the tank. Use a plastic lid or a gutter screen as the grate that sits under the gravel. If using a lid, drill it with numerous holes. The back of the grate needs to sit against the back of the fish tank.

    • 2

      Cut one to two PVC pipes to the height of the fish tank, but shorter than the water expected water level. Use one PVC tube for a small tank and two on either side in a larger tank. Sand a PVC elbow on one side, insert the PVC pipe and attach the PVC pipe and elbow to the back of the undergravel grate with a stainless steel nail. Use pipe appropriate for the size of your tank, probably less than an inch.

    • 3

      Split two PVC pipes in half lengthwise making four halves. Trim the halves to the length of the tank and attach the cut pipes open side down to the grate using aquarium sealant or stainless steel nails.

    • 4

      Place the assembled filter on the bottom of the tank and stabilize the grate with a few cups of gravel. Add an airstone the tube to circulate the air and begin the filtering process. Airstones are available in pet and aquarium stores. Finish adding gravel, so you have 3 to 4 inches, which is enough to secure plants.