Spring Koi Pond Start-Up Guide: Safe Filter Restart & Feeding

🌷 Spring Pond Preparation and Start-Up

Spring is the most dangerous time for Koi health. As the water warms, the fish’s metabolism wakes up faster than the beneficial bacteria in your biological filter. This creates an enormous risk for a deadly Ammonia or Nitrite spike. The key is slow, gradual action.

1. The Essential Spring Clean

Perform a partial clean when the water is cold (below $10^\circ\text{C}$ $50^\circ\text{F}$ ) to minimize stress on the fish before they become fully active.

Remove Sludge: Use a net or a pond vacuum to gently remove accumulated leaves and sludge from the bottom. Do not stir up the bottom too aggressively.
Partial Water Change: Perform a $20\%-30\%$ water change using a dechlorinator. This replaces mineral-poor water and removes dissolved organics that built up over winter.
Trim Plants: Remove dead foliage and trim back marginal plants.

2. Re-activating Filtration and UV

Filter Start: If your biological filter was shut down, restart the pump when the water temperature consistently hits $8^\circ\text{C}$ ( $46^\circ\text{F}$ ). Do not clean the media yet—allow the surviving bacteria to colonize slowly.
Filter Crash Protocol: Dose the pond with a high-quality bacteria starter (biological booster) to accelerate the recovery of the biological filter.
UV Light: Only turn on the UV Clarifier after the filter has run for one week. Turning it on too early can kill the beneficial bacteria suspended in the water column that are trying to reach the filter media.

3. Gradual Feeding (The Golden Rule)

Follow the seasonal temperature chart from the Koi Feeding Guide:

Below $8^\circ\text{C}$ ( $46^\circ\text{F}$ ) DO NOT FEED.
$8^\circ\text{C}$ to $15^\circ\text{C}$ ( $46^\circ\text{F}$ to $59^\circ\text{F}$ ) Begin with tiny amounts of Wheatgerm only, 2-3 times per week. The food must be highly digestible to avoid rotting in the slow digestive tract.
Monitoring: Test water parameters daily during this phase. If you see any Ammonia or Nitrite, stop feeding immediately until the filter catches up.