Kennie D’s homemade biofilter for the Aquaponics system described in this post. Two videos here, one biofilter without aeration tube and one with aeration. Also, very cool explanation about the chemistry involved in turning ammonia (from fish excretions) to nitrites and then to nitrates for the plants. This one has no aeration.
This one has aeration tube plus narration of the chemistry.
Kennie D is the author of this post.