What Are the Causes of High Ph Levels in Ponds?

Various sources in a pond can cause high pH levels. Pond fish prefer a pH at 7 or slightly, and the pH must remain stable for fish to stay healthy. A pH above 9 can kill fish. Identifying the cause of high pH quickly can save their lives.

  1. Definition

    • The pH balance of water refers to the measurement of acidity or alkalinity in a pond. The pH scale has 14 numbers with 7 at the middle of the scale as neutral. The lower the number, the more acidic the water. The higher the number, the more alkaline. A pH above 9 is usually caused by a pollutant.

    Alkaline Water Source

    • Water utilities treat tap water with calcium hydroxide, making the pH slightly higher than 7. This prevents acidic water from corroding pipes by making the water alkaline.

    Buffering System

    • A buffering system like limestone rock, as well as limestone chips in the pond filter, can cause alkaline water, or a pH above 7. However, a buffering system will keep the pH stable and below dangerously high levels.

    Lack of Carbon Dioxide

    • Excessive algae can consume high levels of carbon dioxide in the pond water and raise the pH, sometimes dangerously high.

    Causes of Excessively High pH

    • Pollutants that send the pH to 9 and above often are exposed cement work or builder's lime.