Tips on keeping your garden pond algae free
This is a very timely topic. During prolonged hot, sunny weather, algae can multiply rapidly because of increased sunlight, warm water temperatures and excess nutrients in the pond. In this article we will discuss how to prevent the conditions that allow algae to thrive.
This summer is reported to be one of the warmest across many parts of England. The perfect weather for outdoor activities, but how do garden pond inhabitants cope?
A common myth that needs to be bust is 'Algae means my pond is unhealthy'. But in reality, a small amount of algae is perfectly normal and even beneficial. It produces oxygen and forms part of the pond's natural food chain. Problems only occur when algae grow excessively, usually because the pond contains more nutrients than aquatic plants can use.
How to Prevent Excessive Algae Growth
Increase Shade
Algae depend on sunlight to grow. Ponds sited where they get little shade in the summer daytime hours, may suffer an increase in algae growth
- Aim to shade around 40-60% of the pond surface.
- Introduce floating plants such as water lilies, frogbit or water lettuce (where appropriate).
- Plant taller marginal plants around the pond.
- Consider a pergola or carefully positioned shrubs if the pond receives full sun all day.
Remove Organic Debris
Dead leaves, grass clippings and dying aquatic plants gradually rot. Less decaying matter in your pond means fewer nutrients for algae.
Regularly remove:
- Fallen leaves
- Dead plant material
- Blanket weed
- Excess sludge from the pond bottom
Keep Water Moving
Stagnant water warms quickly and encourages algae.
A fountain, waterfall or pond pump improves:
- Water circulation
- Oxygen levels
- Overall pond health
Moving water also makes it more difficult for surface algae to establish.
Add More Oxygenating Plants
Healthy aquatic plants compete directly with algae for nutrients.
Examples include:
- Hornwort (Ceratophyllum demersum)
- Spiked Water Milfoil
- Water Crowfoot
These oxygenating plants help keep the pond naturally balanced.
Why is my pond green even though I have a filter?
During hot weather the biological filter works harder. It is, therefore important to check it regularly through the summer months.
- Clean mechanical filter sponges regularly.
- Don't wash biological media in tap water, as chlorine can kill beneficial bacteria.
- Ensure pumps are running efficiently.
New ponds commonly experience green water during their first few months. This is a natural part of establishing the pond's biological balance and usually improves as plants mature and beneficial bacteria become established.
Summer Heat Tip
During periods of prolonged hot weather, avoid making major changes to your pond. Instead, provide shade, maintain good aeration, remove decaying organic matter and top up evaporated water gradually. A stable pond ecosystem is far more effective at controlling algae than repeated chemical treatments.
Flexible rubber pond liners are well known for their durability and resistance to UV rays. Whereas PVC liners have a shorter expected lifespan than premium rubber pond liners because prolonged exposure to sunlight and weathering gradually causes the material to lose flexibility.
For more help and advice on pond care and maintenance, please visit Pond Liners Online Blog post on caring for your garden pond during the summer months.
