Step-by-Step: Building a DIY Biological Pond Filter with Peat and Lava Rock

Materials

• Plastic container (~20 gal)
• Submersible pump
• Lava rock (2–3 bags)
• Pond peat (1 bag)
• Filter floss (AC filter media)
• Nylon mesh bag

Assembly

1. Place pump in container bottom.
2. Cover pump with lava rock.
3. Put peat in mesh bag; set on lava rock.
4. Add another lava rock layer.
5. Top with filter floss cut to fit.
6. Run pump outlet to pond (waterfall or return).

Operation

Water flows up through media, polishing and biofiltering. Rinse floss weekly. Replace peat yearly.