How to Remove Algae from Your Pond

Algae can pose a common challenge in koi ponds, affecting both the aesthetics and water clarity. Its presence not only diminishes the visual appeal of the pond but can also jeopardize the health of your koi by creating an unfavorable environment. This ultimate guide outlines various types of algae and provides the best methods for their effective removal from your pond.

Types of Algae

There are several types of algae that can thrive in a koi pond, including green algae, string algae, and blanket weed. Green algae typically manifests as a green film or scum on the water’s surface. String algae appears as long, thin strings hanging from rocks, plants, or pond surfaces. Blanket weed is a rapid-growing algae that can cover the pond surface entirely, obstructing light and depleting oxygen levels.

Preventing Algae Growth

The most effective approach to maintaining a clear pond is to prevent algae growth. Follow these steps:

  1. Maintain a Healthy Bacterial Balance: Foster a healthy balance of beneficial bacteria in the pond.
  2. Ensure Circulation and Aeration: Keep the pond well-circulated and aerated to discourage algae development.
  3. Sunlight Control: Manage the amount of sunlight entering the pond, considering shade options.
  4. Regular Cleaning: Keep the pond clean, removing excess organic matter that can contribute to algae growth.
  5. Pond Cover Usage: Use a pond cover to limit sunlight exposure and minimize algae proliferation.

Removing Algae

If algae are already present, employ these methods for effective removal:

  1. Manual Removal: Physically skim algae off the water surface or brush it from rocks and pond surfaces. Suitable for small amounts, not recommended for blanket weed.
  2. Chemical Treatments: Algaecides and copper-based treatments can effectively kill algae, but use caution as they may be toxic to koi and other aquatic life.
  3. UV Sterilization: Install a UV sterilizer in the pond filtration system to control and eliminate algae. UV light passing through the system effectively kills algae, providing a safe removal option.
  4. Natural Methods: Experiment with natural approaches, such as adding barley straw or incorporating specific aquatic plants that naturally compete with algae for nutrients.


Removing algae from your koi pond is crucial for maintaining a healthy and visually appealing environment for your fish. By adopting preventative measures and employing suitable removal methods, you can keep your pond algae-free and ensure the well-being of your koi.


Matthew Adlington

By Published On: 21 July 2022