Using a Stream as a Biological Filter for a Duck Pond

Stream as Filter

A 35-ft stream with ¾–1½ inch river rock at 6,000 GPH provides massive surface area for nitrifying bacteria—effectively a trickle filter. For a duck pond (high nutrient load), this is excellent.

Intermittent Flow

Turning the pump off 12 hours/day is fine; biofilms survive damp periods. Ducks benefit from daytime aeration; nighttime off saves electricity.

Enhancements

• Add marginal plants in the stream (pickerelweed, iris) for nutrient uptake.
• Include a settling basin at the top to catch duck waste solids.
• Monitor ammonia; if it rises, run 24/7 or add a dedicated biofilter.