The grass-like algae in your pond is most likely string algae.
Understanding String Algae
String algae, also known as filamentous algae, is a common organism found in various water features, including backyard ponds. It often appears as long, green, hair-like strands or mats that can grow quickly and cover surfaces in the water.
As referenced, this type of algae:
- Is an organism that commonly hangs out around water features.
- Feeds on excess nutrients in the water.
- Is a natural, normal, expected, and beneficial part of a balanced ecosystem pond, even though many pond owners might not like how it looks aesthetically.
While its appearance can sometimes be unsightly, string algae plays a role in consuming excess nutrients like phosphates and nitrates, which helps improve water quality.
Why Does String Algae Grow?
String algae thrives when there is an abundance of nutrients in the water, combined with sunlight. Common sources of excess nutrients include:
- Fish waste
- Decaying leaves and other organic matter
- Runoff from surrounding landscapes (fertilizers, soil)
- Excessive fish feeding
Sunlight fuels the growth process (photosynthesis), so ponds in full sun are often more prone to algae blooms than those with partial shade.
Managing String Algae
While string algae is a natural part of a pond ecosystem, excessive growth can become problematic, potentially clogging filters or overwhelming beneficial bacteria. Here are some common strategies to manage its growth:
- Manual Removal: Physically remove large clumps of algae using a net or rake. This provides immediate visual improvement and removes nutrients captured by the algae.
- Reduce Nutrients:
- Avoid overfeeding fish.
- Remove decaying leaves and debris regularly.
- Ensure proper pond filtration.
- Consider using beneficial bacteria treatments that consume excess nutrients.
- Add Aquatic Plants: Introduce a variety of aquatic plants (like submerged plants, floating plants, and marginals). Plants compete with algae for nutrients, helping to keep algae growth in check. Aim for covering about 40-60% of the pond surface with plants.
- Increase Aeration: Good oxygen levels can support a healthy ecosystem that is less favorable to rampant algae growth.
- Limit Sunlight: Provide shade over the pond using pond plants, shade sails, or strategically placed landscaping.
Managing string algae is often an ongoing process focused on maintaining a healthy, balanced pond ecosystem rather than attempting to eliminate it entirely.
