DIY Carbon Filters for Aquariums

Filtering is a crucial operation in any aquarium that removes both the physical and soluble chemical wastes from the water. Remnants of rotting food, plant matter, fish waste and algae are removed to prevent the build-up of ammonia, nitrates, nitrites and other compounds. Many filters are mechanical units that contain activated carbon to remove these contaminants. A do-it-yourself carbon filter is easy to construct with a few common materials.

  1. About Carbon Filters

    • Carbon is an excellent material for removing odors and discoloration from aquarium tanks. It absorbs many residues including chloramines, organic molecules, heavy metals and medications used to treat the fish that should not remain in the water for long periods of time, according to the Aquatic Community website. Carbon̵7;s advantage is that it has microscopic pores that capture and hold the contaminants as the water passes over the filter. Once the carbon has absorbed as much as it can hold, it must be changed.

    DIY Carbon Filter Materials

    • You will need a plastic container of some kind. This container can be as simple as the cut bottom half of a soda bottle or some other type of clear plastic box. You will need a drill and drill bit to create holes for water input and output, as well as two ¾-inch barbed fittings. Plastic tubing, about ¾ inch in diameter, is also necessary to allow the flow of water through the filter mechanism. The tubing is secured to the openings in the container with 100 percent silicone adhesive that contains no chemicals that can leach into the tank and hurt your fish. Purchase a pump to move the water through the filter container. Choose a pump size suitable for the size of your aquarium. Also purchase aquarium floss to fill the rest of the filter container after inserting the carbon.

    Assembling the Container

    • Drill a ¾-inch hole at one end of the plastic container and insert a barbed fitting for your input tubing. At the other end of the box, drill another hole and insert the other barbed fitting for the output tube. Seal the two fittings with silicone adhesive and allow them to dry. Attach a 2-inch piece of plastic tubing to each fitting and seal it with the adhesive.

    Adding the Carbon

    • Place the carbon into a nylon bag. A piece of pantyhose is perfect for this purpose because it has very small holes to allow the water to flow freely over the carbon pieces. Tie the top of the nylon bag tightly with string or a plastic tie. The carbon should fill the plastic container about halfway. Place the bag into the plastic container. Fill the rest of the container with the aquarium floss. Attach the pump to the input tubing of your DIY carbon filter.

    Installing the Filter

    • Lower the carbon filter into the sump and attach it to the side of the tank with adhesive. Position the box in an area of the sump that is easy to reach so that you can remove any build-up of algae or other materials.