Clearing Muddy Water in a New 100‑Gallon Pond with Koi and Clay‑Potted Plants

Cause of Cloudiness

New 100‑gal pond, 4 koi, plants in aquatic clay. Water turned muddy; filter runs 24/7; “clear‑up” tablets failed.

Repot plants – Remove clay, use plain clay soil + pea gravel top‑dressing, or Schultz aquatic soil.
Clean filter – It’s likely clogged with clay fines.
30% water change – Reduces suspended solids.
Flocculant – AccuClear (Aquarium Pharmaceuticals) clumps fines for filter removal.

Pond too small for koi – Adult koi need 1,000+ gal. Plan upgrade.
Expect algae bloom – New pond + koi + few plants = green water. See algae guide.
Full clean‑out if needed – Shop‑vac bottom; hold fish in kiddie pool with saved water.

Pond and Water Gardening: Winterizing a Koi Pond in North Carolina; Milky White Water in New Pond: Causes and Cures; Persistent Green Algae in Large Koi Pond: Filter Maturity and Maintenance; Fixing Cloudy Pond Water and Black-Coated Waterfall Rocks; Kidney Pond (3×1 ft) Green Algae Constantly; Cesspool-Smelling Large Pond: No Outlet = Stagnation Death; Clearing Muddy Water in a Natural Pond After Construction and Heavy Rain; Clearing Muddy Water in a New Texas Pond After Rain Runoff; Tea-Colored Pond Water: Mulch Tannins or Black Water?; Clearing Muddy Garden Pond Water: Causes and Solutions

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