How To Get Rid Of String Algae

How To Get Rid Of String Algae

There are plenty of reasons to keep a pond or outdoor water feature – it’s relaxing to sit by, they provide a unique ecosystem for plants and animals, and they can add beauty to any backyard. But there’s one thing that every pond owner dreads: the appearance of unsightly algae.

One of the primary culprits in pond algae growth is string algae. This type of algae forms long, hair-like strands that can quickly overtake a pond and ruin its appearance. It often thrives in warm, sunny conditions and can be difficult to get rid of once it takes hold.

But don’t worry – there are steps you can take to control and even eliminate string algae from your pond. Let’s take a look at some of the top method for getting rid of string algae in your pond, and some ways you can ensure they don’t return!

What is String Algae?

String algae, also known as filamentous algae, is a type of green algae that grows in long, hair-like strands. It thrives in nutrient-rich environments and can quickly overtake your pond if left unchecked. 

While a small amount of string algae is normal and even beneficial for your pond's ecosystem, an overgrowth can be unsightly and harmful to your fish and plants. Over time, it can deplete oxygen levels and block sunlight from reaching submerged plants, causing them to die off.

What Causes String Algae Growth?

To effectively combat string algae, it's essential to understand what fuels its growth. The primary culprits behind string algae overgrowth are excess nutrients in your pond water, particularly nitrates and phosphates. These nutrients can come from various sources, such as:

  • Fish waste
  • Uneaten fish food
  • Decaying organic matter (e.g., leaves, dead plants)
  • Runoff from fertilizers or lawn treatments

When these nutrients accumulate in your pond, they create the perfect environment for string algae to thrive. For instance, if you find that string algae growth is most prevalent near your pond's waterfall or filter, it could be a sign that excess nutrients are getting trapped and fueling the algae's growth.

Are String Algae Good For Ponds?

While string algae may seem like a nuisance, they can actually provide some benefits to your pond ecosystem. For instance, they can help oxygenate the water and provide food for certain aquatic animals. However, when string algae overgrow, it can have negative impacts on your pond.

The key is knowing your pond’s purpose (for aesthetics, recreation, or wildlife habitat?) and finding the right balance of string algae. Too much can be harmful, but a healthy amount can actually improve the overall health of your pond.

How to Get Rid of String Algae

Now that you understand the root causes of string algae overgrowth let's dive into the most effective methods for getting rid of it:

1. Manual Removal

The simplest and most direct method is to physically remove the string algae from your pond. Use a pond rake or skimmer to collect as much of the algae as possible, being careful not to disturb your fish or plants in the process. Regular manual removal can help keep string algae growth under control.

2. Boost Your Filtration

Ensuring your pond has an adequate filtration system is crucial for maintaining clean, clear water. A high-quality filter will help remove excess nutrients and debris from the water, reducing the food sources for string algae. Consider upgrading your filtration system or adding a UV clarifier to help control algae growth.

3. Reduce Nutrient Input

To prevent string algae from reappearing, minimizing the nutrients entering your pond is essential. Here are a few tips to help you avoid feeding the algae it’s favorite food sources:

  • Avoid overfeeding your fish, and remove any uneaten food promptly
  • Use a pond vacuum to remove decaying organic matter from the bottom of your pond
  • Regularly clean your pond's filters to ensure they're working efficiently
  • Consider using pond plants to absorb excess nutrients

4. Introduce Beneficial Bacteria

Fight fire with fire! (Or bacteria, in this case.) Adding beneficial bacteria to your pond can help break down organic matter and consume excess nutrients, reducing the food sources for string algae. Look for pond-specific bacterial additives that contain a blend of helpful microorganisms to create a balanced ecosystem.

5. Use Natural Algae Control Methods 

If manual removal and preventive measures aren't enough, there are several natural algae control methods you can try:

  • Barley straw: As barley straw decomposes, it releases compounds that can inhibit algae growth. Place a barley straw bundle or liquid extract in your pond to help control string algae.
  • Pond dye: Adding a natural pond dye can help limit sunlight penetration, reducing the ability of string algae to photosynthesize and grow.
  • Algaecides: As a last resort, you can use a pond-safe algaecide to control string algae growth. Be sure to choose a product specifically designed for use with fish and follow the instructions carefully.


What kills string algae without harming fish?

To control string algae without harming your fish, consider physical removal using a pond rake or skimmer, improving filtration to remove excess nutrients, and adding beneficial bacteria to outcompete algae for resources. Natural algae control products like barley straw or pond dye can also be used.

What causes string algae to grow in ponds?

String algae thrive on excess nutrients in pond water, particularly nitrates and phosphates. These nutrients can come from various sources, including fish waste, uneaten fish food, decaying organic matter like leaves and dead plants, and runoff from fertilizers or lawn treatments.

Is string algae harmful to fish or plants?

While string algae isn't directly harmful to fish or plants, an overgrowth can cause several issues. As the algae decomposes, it reduces oxygen levels in the water, which can stress fish. String algae can also clog filters and pumps, reducing their efficiency.

Can UV clarifiers help control string algae?

While UV clarifiers are more effective at controlling single-celled algae (green water), they can still be beneficial in managing string algae. UV clarifiers help improve overall water quality by reducing the number of free-floating algae spores, which can indirectly help control string algae growth.

How often should I remove string algae from my pond?

The frequency of string algae removal depends on the severity of the growth and your pond's specific conditions. As a general rule, it's a good idea to remove as much string algae as possible whenever you notice it starting to take over.

Say Goodbye to String Algae with Living Water Aeration

Living Water Aeration is dedicated to helping pond owners like you achieve the clear, beautiful water you've always dreamed of. String algae can be a stubborn and frustrating problem, but with the right knowledge and tools, you can take control of your pond's health and appearance.

As your trusted partner in pond care, we offer a wide range of products and solutions designed to help you combat string algae and maintain a thriving ecosystem. We have everything you need to transform your pond from high-quality aeration systems that promote healthy water circulation to beneficial bacteria and natural algae control products.

Don't let string algae take over your outdoor oasis. Explore our full range of pond care solutions and discover how Living Water Aeration can help you achieve the pond of your dreams. While you're there, check out our blog for more expert tips and advice on maintaining a healthy, vibrant pond!

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