How to Design a Fish Tank Filter

Building your own filter is a cost-efficient way to raise your fish-keeping hobby to a new level. Sponge filters, on average, last longer than carbon-based ones and only need to be changed every four to six months to maintain the optimum health levels necessary for a successful fish tank. Homemade sponge filters can easily be customized to fit any size aquarium and come in a multitude of sizes and colors, making it possible to design the ideal filter for your specific tank set-up.

Things You'll Need

  • Square filter sponge
  • X-Acto knife
  • Black marker
  • Plastic tube
  • Nail
  • Hammer
  • Piece of Styrofoam the size of open-end of tube
  • Powered air pump and hose
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Instructions

  1. Instructions

    • 1

      Cut the filter sponge in half, making two triangle-shaped pieces with the X-Acto knife. If the pieces are too large for your size tank, cut the pieces in half once more, leaving you with four smaller triangular pieces. Store the unused pieces to be changed when necessary.

    • 2

      Size the plastic tube up to the filter sponge, marking out how much will be inserted into the filter with the marker. Dot the tube down one side with the marker, then hammer the marks with the nail and hammer. Drive the nail through the tube so it creates two holes at one time.

    • 3

      Push the piece of Styrofoam into the end of the tube that will be submersed into the filter sponge. Cut off any excess with the X-Acto knife. Push your finger down into the filter sponge, creating an indent. Insert the tube the rest of the way into the filter, keeping the holes down into the sponge.

    • 4

      Insert the powered air pump on top of the plastic tube. Connect the air hose to the outlet on the pump, pointing the outlet so the outgoing water flow goes to the surface of the tank. Mount the assembled filter into the tank, then fill the tank with water. Plug the filter in, and make any necessary changes as needed.