DIY Bead Filter Aquacultures

Aquaculture is the practice of raising aquatic animals for commercial purposes, including for food, wildlife restocking or the aquarium trade. In any aquaculture system, efficient removal of organic waste is critical to the health of the cultured animals. In particular, encouraging the biological filtration process known as the "nitrogen cycle" is important. The nitrogen cycle is the process by which bacteria change the highly toxic ammonia secreted by fish to slightly less toxic nitrite. In the final stage of the process, the nitrite is converted to nitrate, which is only toxic in high concentrations. A bead filter assists in this process.

Things You'll Need

  • Plywood
  • Two-by-fours
  • Water-safe epoxy
  • Nylon screen
  • Beads
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Instructions

    • 1

      Sketch out your bead filter according to the size of filter you will need. The size is determined by the amount of food you add to your aquaculture system on a daily basis. For every 100 lbs. of food per day, the size of the bead filter chamber should increase by about 48 cubic feet. So if you use 500 lbs. of food per day, the chamber should be 240 cubic feet.

    • 2

      Build the filter using plywood and two-by-fours. Construct a frame using the two-by-fours. Screw the plywood on the inside of the frame to hold the water. Wood has the advantage of being cheaper and easier to work with than acrylic or glass.

    • 3

      Add the bottom support plate for the beads. Usually a two-by-four frame covered with a nylon screen will suffice. Just make sure it has enough support to hold the beads. This support plate will hold the beads above the water line of the filter so that the water trickles down through the beads.

    • 4

      Coat the inside of the plywood box with marine-safe epoxy. You will need about four coats to fully seal the wood. Coat the outside as well so that the dampness will not rot the wood. Let the epoxy fully cure.

    • 5

      Add your beads into the bead chamber on top of the screen. Bead size is important as a greater surface area will provide a greater area for bacteria to grow and increase filter efficiency. Beads come rated as Type A, B, C or T. For maximum filter efficiency, use Type B, C, or T. Type A beads are too large and will not provide the best filtration.

    • 6

      Build a spraybar above the beads using PVC pipe. Here, one inlet pipe is split into many smaller pipes that hang horizontally over the beads. Drill small holes in these smaller pipes so that the water sprays out on the bead bed. The bacteria growing on the beads need oxygen as well as water, and providing them some access to air will help. This is why the beads should not be completely submerged in water.

    • 7

      Add a drain from the chamber underneath the beads leading back into the aquaculture system or another type of filter. The water exiting the bead filter should be free of ammonia and nitrites.