Fixing Dead Zones in a Koi Pond: Skimmer Placement and Circulation

The Golden Rule: Skimmer Opposite Waterfall

Place the skimmer (intake) directly across from the waterfall (return). This creates a circular current that sweeps the entire pond, eliminating stagnant corners where debris settles.

Bottom Drain Not Required

A well-designed circulation pattern with a mid-water intake (skimmer) and bottom return (or bottom drain *to* the filter) moves bottom water effectively. Your submersible pump stirring the bottom may be disrupting the surface skimming flow.

Diagnose Your Flow

• Float a ping-pong ball or leaf—does it travel from waterfall to skimmer in a smooth arc?
• Check for "dead zones" where debris accumulates.
• Ensure pump flow matches filter rating (5,200 GPH pump → filter rated for 5,000+ GPH).

Solutions

1. Reposition the submersible pump to *push* water toward the skimmer, not away.
2. Add a second skimmer (floating or wall-mounted) if the pond is wide.
3. Consider a bottom drain retrofit feeding the external filter—best done during off-season.

Send photos and measurements if you want a specific layout review. Good circulation is the foundation of clear water and healthy fish.