How to Treat Green Hair Algae

There are many different species of green algae that can take on a hair-like appearance, but most green hair algae belong to the genus Oedogonium. This common scourge of the fish tank forms long strings, giving it a hairy appearance. It is also known as string algae. Green hair algae in your aquarium can sneak up on you. This article details why this type of algae occurs and explains how you can effectively treat it. We also explain how to prevent it from happening again!

But Firstly…What is Green Hair Algae?

Green hair algae is a type of algae that attaches itself to rocks in ponds, liners, and waterfalls. This is also a common issue for aquarium owners with rocks at the bottom of their tanks. This type of algae, otherwise known as hair algae, looks like string or hair-like filaments and, if left untreated, can grow to vast lengths in a pond or aquarium.

Symptoms of Green Hair Algae

Before delving into the solutions, it’s essential to recognize the symptoms of a green-haired algae infestation. Some signs include:

  1. Stringy Filaments: Green hair algae grow in long, hair-like strands attached to aquarium surfaces.
  2. Slimy Texture: Upon touch, this algae can often feel slimy and can cling to your fingers.
  3. Rapid Growth: An explosion of green strands in your tank in a short period is a clear sign.
  4. Uneven Coverage: These algae don’t grow uniformly. Instead, they often cluster in certain areas, especially where water flow is reduced.

What Causes Green Hair Algae?

When green hair algae first start to grow, you can’t see it, but if you scoop it up, you can see really small pieces of it start to cultivate at the base of your tank. String algae can sometimes seem like it has come out of nowhere, especially for hobbyists experiencing the issue for the first time. However, there is always an underlying cause. Here are the main causes of hair algae:

  • Poor tank maintenance
  • Increase in pH
  • Increase in phosphorus
  • Excessive plant growth
  • Overstocking of fish in the aquarium
  • Introduction of foreign materials in your tank


Recognizing an algae problem is the first step to rectifying it. Here’s how you can diagnose green hair algae:

  1. Visual Inspection: The most straightforward method is to look. If your tank has stringy, green tendrils, you’ve got an issue.
  2. Water Tests: Check your water for elevated nitrate and phosphate levels. High levels can indicate conditions that favour green hair algae growth.
  3. Check Light Exposure: Excessive or irregular lighting can contribute to algae growth. Ensure your tank isn’t exposed to direct sunlight or left with artificial lights on for extended periods.

How to Remove Green Hair Algae

There are many methods to remove string algae from your aquarium, and they are all effective, but the one you choose may depend on how bad the case is. Here are some solutions below,

Siphon out & Gravel Sucking – poor maintenance is the issue behind hair algae, and prevention is key. Ensure you have the balance of bacteria and phytoplankton and clean/gravel sucking the tank frequently to keep the bacteria cultivating. Use this method if the case is mild to extreme, and do it first to remove as much as you can before attempting other methods. Also, use this method regularly as a prevention tool.

Lights out – If the green hair algae are not overgrown, keep the tank dark for 24-48 hours to prevent photosynthesis. During this time, they should die out, and it should not affect the other plants in the tank – make sure the other plants and fish have enough food supply (phytoplankton/zooplankton) throughout this time. Use this method if the case is mild.

Phytoplankton – dose with micro magic phytoplankton to starve the hair algae out and restore balance! Having a regular healthy balance of phytoplankton in your tank will also help to ensure the string algae does not regrow. We have both Freshwater MicroMagic and Marine Micro Magic phytoplankton available. Use this method if the case is mild to extreme.

UV Filter – If the case is bad, run a UV filter so that as the little pieces go past the UV, it kills them. 15 seconds of exposure to UV is enough to kill the hair algae. We do not sell UV filters, but you can buy them online or in aquarium shops. Use this method if the case is moderate to extreme.

Enter The Natural Solution: Amphipods – Nature’s Algae Scrubbers

While the methods listed above are tried and true, there’s a new, natural way to combat green hair algae, and it’s already making waves in the aquarium community.

Why Consider Amphipods?

  1. Natural Algae Control: Unlike other methods involving chemicals or equipment, amphipods naturally control green hair algae. These creatures are known to devour this algae, making them a perfect addition to tanks plagued by this issue.
  2. Beneficial for Marine Life: Alongside their algae-eating benefits, amphipods serve as a nutritious food source for various marine species, ensuring they offer multiple benefits once introduced into your tank.
  3. Self-Sustaining Population: The beauty of the amphipod solution lies in its sustainability. Starting with just a handful, they breed and multiply, offering a long-term solution to persistent algae problems.

Integrating Amphipods Into Your Green Hair Algae Treatment Plan

  1. Acclimate Them Properly: Gradually introduce the amphipods to your tank’s water conditions.
  2. Monitor Their Activity: As they get to work, you’ll see a reduction in the green hair algae. Monitor them to ensure they’re thriving and doing their job.
  3. Combine With Other Methods: While amphipods are effective, they work best with other treatments, especially if your algae problem is severe. Consider combining their use with methods like siphoning or phytoplankton dosing for best results.

Adding ALF’s Scrubber Pack to your green hair algae treatment arsenal means achieving a clean, vibrant tank that has never been more natural or effective. Remember, a multifaceted approach combining natural and traditional methods often yields the best results.

ALF’s Scrubber Pack: A Game-Changer in Algae Treatment

Responding to the need for natural algae solutions, ALF presents the Amphipod Scrubber Pack. This pack offers a set of 5 special amphipods, each with an insatiable appetite for green hair algae.

Ideal for smaller tanks between 30-40L, this initial pack of 5 will soon breed and multiply, ensuring continuous algae control.

How to Prevent Green Hair Algae

Prevention is the best approach to most problems. Here are preventative measures:

  1. Regular Maintenance: Regularly clean and vacuum your tank. Ensure you remove any debris, uneaten food, and decaying plant matter.
  2. Optimize Lighting: Ensure your tank has a regular light cycle. Consider timers to regulate the light your tank receives if using artificial lights.
  3. Water Quality: Regularly test your tank’s water for phosphates and nitrates. Use quality filters and consider phosphate removers if necessary.
  4. Limit Nutrients: Overfeeding fish can lead to excessive nutrients in the water, favouring algae growth. Feed in moderation and ensure all food is consumed.
  5. Introduce Algae Eaters: Consider adding natural algae eaters to your tank, such as the amphipods from ALF’s Scrubber Pack, to keep any budding algae growth in check.

By understanding the symptoms, diagnosing the problem early, and adopting preventive measures, you can keep your tank vibrant, clean, and free from the grip of green hair algae.

If you have any further questions on hair algae or general tank maintenance, please get in touch with us at