Homemade Fish Filters

Tank filters are necessary for keeping fish healthy. A filter helps purify the water by removing toxins. Commercial filters can be pricey, but a homemade filter can be made cheaply and will be just as effective at removing toxins. Homemade filters can also be used as a back up for tanks that already have a commercial filter. This is especially helpful for big tanks with small commercial filters, or tanks holding many fish.

  1. Materials

    • The materials necessary to build a fish tank filter are very inexpensive and are probably already laying around the house, or in the recycle bin. Find a plastic container, such as a butter/margarine container or an ice cream container, a plastic soda bottle, an air pump hose, and gravel. Depending on the design of the filter, an air pump or water pump will be used. (see references 1, 2 and 4)

    Mechanical and Biofiltration

    • Aquarium filtration systems typically have two functions: Mechanical filtration and a biofiltration. Mechanical filtration removes debris, such as fish feces and decaying plant pieces, from the water. Biofiltration provides a place for colonies of beneficial bacteria to grow (see reference 3). Beneficial bacteria eat toxins out of the water, like nitrogen and ammonia, which can be toxic to fish in high quantaties. A biofilter full of beneficial bacteria is necessary to maintain healthy water chemistry for fish to survive.

    How to assemble the filter when using an air pump

    • A simple biofilter, (a filter that removes toxins) can be created using a soda bottle, a plastic container such as a butter container, an air pump with a hose, and an air stone. An air stone is a long stone with small holes cut into it. It is used with an air pump and hose to pump small water bubbles into water and oxygenate the water so the fish can breath. To assemble the filter, cut the soda bottle in half. Put the soda bottle in the center of the open plastic container. Place the air stone, which should be attached to the air pump hose, under the soda bottle half. The air bubbles will be released through the bottle's top. Fill gravel around the soda bottle inside the plastic container, do not put gravel inside the soda bottle which would obstruct the air and water flow. Place the homemade filter in the tank. The moving air bubbles create a water current, pulling the tank water into the filter. The gravel will grow colonies of beneficial bacteria that eat the toxins out of the water (see reference 1 and 2).

    How to assemble using a water pump

    • Water pumps, although more costly than an air pump, are more effective at filtering debris and purifying the water. Cut off the bottom of the soda bottle, in a way that the two pieces can be placed back together. Cut a small hole in the bottom of the bottle, small enough for the water pump tubing to fit through, and cut another hole in the bottle cap. Fill the bottle with gravel, and place filter mesh inside the bottle. The gravel will grow beneficial bacteria and purify the water, and the filter mesh will catch debris. Place the pump tube into the hole in the bottom of the soda bottle, this will pull the dirty tank water into the homemade filter. Attach the homemade filter to the inside of the tank with the cap side of the bottle down so that the filtered water can flow through the cap hole and back into the tank. Put the water pump into the tank and turn it on (see reference 4).