DIY Filter for a 125-Gallon Goldfish Pond Under $100

Build a Bucket Filter

1. 2 × 5-gallon buckets with lids.
2. Drill 1-inch holes in bottom of upper bucket.
3. Fill upper with lava rock or bio-balls.
4. Pump water into upper bucket; it trickles through media into lower bucket, then returns to pond.
5. Add a sponge pre-filter on pump intake.

Cost

Buckets $10, lava rock $15, pump $40–60, tubing $10 = <$100.

Maintenance

Rinse media in pond water monthly. Clean sponge weekly.

Resource

Filter plans: koi-z-are-us.20m.com (George's site).