How to Make a Homemade Fish Tank Filter

Filters are critical to the health of your aquarium's residents, removing physical and chemical waste products and making maintenance easier. They also provide life-giving oxygen to your pets, which are being kept in relatively small, closed volumes of water.
This simple aquarium filter will cost little to make. It works because the bubbles create uplift as water is drawn through the aquarium, through the charcoal and filter wool, and then through the holes in the bottle, thereby filtering your water.

Things You'll Need

  • Empty plastic 2-liter bottle Scissors or hobby knife 7/8-inch to 1-inch PVC pipe Aquarium air tubing Untreated sponge Aquarium charcoal Aquarium filter wool Aquarium air pump
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Instructions

    • 1

      Remove the label from the 2-liter bottle. Cut off the top 4 1/2 inches of the bottle with a hobby knife or scissors. This will become the inner bottle, Remove the cap and discard it.

    • 2

      Poke numerous holes in the top portion of the inner bottle. Make a 1-inch ring of holes all the way around it, just below the neck. A heated fork works well for this because it easily melts the plastic.

    • 3

      Place the inner bottle inside the bottom part of the 2-liter bottle (which becomes the outer bottle) with the neck upright. Push it all the way in toward the bottom until it won't go any further, becoming an inner bottle.

    • 4

      Push about 2 inches of the PVC pipe into the neck of the inner bottle top. Make sure that the PVC fits snugly, and is not so tall that it will break the water's surface.

    • 5

      Thread aquarium air tubing through the PVC pipe until you can see it has been passed completely through the pipe and extends into the inner bottle. Stuff a small piece of sponge into the top of the PVC pipe to hold the air tubing firmly in place. Cut the tubing and attach the other end of it to your air pump.

    • 6

      Dump aquarium charcoal into the outer bottle so that it surrounds the inner bottle top. Add enough charcoal so that it's about 2 inches from the top of the outer bottle. Level it with your fingers.

    • 7

      Fill the rest of the outer bottle with aquarium filter wool, firming it into place with your fingers. Leave about 1/2 inch between the top surface of the wool and the top of the outer bottle.

    • 8

      Set the completed filter into your aquarium. Hold it in place to let it fill up with water. Once filled, it will maintain its position on its own. Turn on the pump, and take pride in having saved yourself lots of money.