Homemade Filter for a Large Aquarium

Fish and marine invertebrate animals, such as starfish, pollute aquarium water with their metabolic waste. Filters remove this toxic organic material, before the creatures in the aquarium become ill. Although many filters are available commercially, you can build your own. According to Alan Jardine, former Chief Conservation Officer at the National Zoological gardens of South Africa, a filter that sits on top of the aquarium using gravity to feed water back into it, works particularly well for large aquariums. These aquariums often have lights suspended from the ceiling above them and no canopy.

Things You'll Need

Glass box, 48-inches long by 4-inches wide by 4.5-inches high, 0.31-inches thick pre-drilled with a 1.5-inch hole in the base plate, in the back right hand corner
One 1-inch bulkhead
Work bench
Two soft towels
One sheet of emery paper
Two panes of glass, 4-inches long by 3-inches high, 0.31-inches thick
Small bottle of acetone
Clean cloth
One tube of non-toxic, 100 percent silicone, 10 fl. Oz
Two match boxes
One roll of masking tape
Scissors
One 5-inch-long, 1-inch-diameter piece of PVC pipe
Aquarium, 48-inches long by 12-inches wide by 16-inches high
GenX -1500 volute submersible pump
2-foot-long plastic tubing, 1.5-inch in diameter
Plastic clamp
Two nylon filter bags containing activated carbon
Two large handfuls of filter wool
Two nylon filter bags of phosphate remover
20 bio balls

Instructions

- 1
  Position the plastic bulkhead in the pre-drilled hole in the glass box's base panel, so that the threaded end points out of the box. The bulkhead gasket will be on the inside of the box. Attach the plastic nut and secure the bulkhead.
- 2
  Lay two large towels on a clean work surface and place the glass box on the towels.
- 3
  Cut the emery paper into strips and use it to sand the edges of both panes of 4-inch-long by 3-inch-high by 0.31-inch-thick glass.
- 4
  Wet the cloth with acetone and wipe the edge of both pieces of glass to remove oils from the glass cutter and any residual dirt from the emery paper.
- 5
  Lay both panes of glass on the towels.
- 6
  Squeeze a continuous thin bead of silicone sealer along the side-edge on both of the 3-inch sides of the first pane of the 4-inch-long by 3-inch-high by 0.31-inch-thick glass.
- 7
  Measure a distance of 16-inches from the side of the glass box, opposite where the pre-drilled hole is. Make a mark on the front and back panes of the glass box. Connect the two marks by drawing a line across the width and along the base of the glass box.
- 8
  Position two match boxes --- an equal distance apart --- along this line.
- 9
  Place the first piece of glass carefully into the glass box and rest it on the match boxes. Smooth out the silicone where the first pane of glass is secured to the front and back panes of the glass box.
- 10
  Cut four strips of tape and use them to hold the first pane of glass in position, by taping the pane to the glass box. There should be an opening between the bottom of the glass pane and the base of the glass box, because the glass pane is resting on the match boxes.
- 11
  Measure a distance of 16-inches from the pane of glass that you have just secured in the glass box. Make a mark on the front and back panes of the glass box at this new distance.
- 12
  Squeeze a continuous thin bead of silicone sealer along the side-edge on both of the 3-inch sides of the second pane of 4-inch-long by 3-inch-high by 0.31-inch-thick glass.
- 13
  Place the second piece of glass carefully into the glass box at a distance of 16-inches from the first glass pane. Smooth out the silicone, where the second pane of glass is secured to the front and back panes of the glass box.
- 14
  Cut four strips of tape and use them to hold the second pane of glass in position, by taping the pane to the glass box, on both front and back walls.
- 15
  Leave the glass box to cure for 24 hours. Remove the tape and match boxes.
- 16
  Push the 5-inch-long, 1-inch-diameter piece of PVC pipe over the threaded end of the bulkhead on the outside of the glass box. Make sure that the join is tight. Spread 1 tsp. of non-toxic, 100 % silicone sealer around the outer joint, to ensure the seal.
- 17
  Run a continuous bead of silicone sealer along the entire top edge of the back pane of the main aquarium. Run a 4-inch-long bead of silicone sealer along the top edge of the right side of the aquarium, beginning at the back corner. Run a 4-inch-long bead of silicone sealer along the top edge of the left side of the aquarium, beginning at the back corner.
- 18
  Carefully place the glass box onto the silicone on the top edges of the main aquarium and press down gently. Leave the silicone to cure for at least 24 hours.
- 19
  Push the 2-foot long piece of tubing over the exhaust nozzle of the return pump. Place the GenX -1500 volute submersible pump into the main aquarium and rest it on the gravel in the back corner, on the opposite side to the pre-drilled hole. Place the free end of the tubing into the glass box and secure it on the glass box rim with a plastic clamp. The tubing must be positioned at the opposite end to the pre-drilled hole.
- 20
  Place two nylon filter bags containing activated carbon into the first compartment of the glass box. This is the compartment on the opposite side to the pre-drilled hole. Place two large handfuls of filter floss on top of the bags of activated carbon.
- 21
  Place two bags of phosphate remover into the second compartment. Place 20 bio balls on top of the bags of phosphate. Aquarium water will be forced to travel down through the activated carbon to move into the second compartment, from where it flows over the glass partition, into the last compartment. The water then feeds via gravity back into the aquarium.
- 22
  Plug the GenX -1500 volute submersible pump into a wall power source and turn it on.