Things You'll Need
- Empty plastic soda bottle
- Utility knife
- Ice cream container
- Fine gravel
- Air stone and tubing
- Aquarium aerator
Instructions
Cut the clean plastic soda bottle in half, discarding the bottom half and bottle cap. Cut wide "V" shapes, about 1 inch long, around the edge of the bottle.
Place the plastic bottle into the ice cream container. If the bottle can't sit straight without tipping over, trim the V shapes until it can. Insert the air stone, with the tubing attached, through one of the V openings, so it sits in the middle of the bottle.
Pour as much fine aquarium gravel as needed into the ice cream container, until it is completely full. Check to see that the soda bottle is still clear, and that the air stone is not obstructed, by looking through the open neck of the bottle.
Attach the air line tubing to an aquarium aerator. Place the container into the aquarium. Place it in a corner, and turn the aerator on. The air flowing up the neck of the bottle creates a gentle drawing current, pulling water through the gravel. This works to trap much of the debris that can foul an aquarium's water quality.
Clean the filter system regularly by removing the container and rinsing the gravel.