White Hair Algae in Aquarium – Causes, Removal & Prevention

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Setting up the ideal aquarium setup is easier than keeping it that way. While nobody wants to deal with algae, everybody will eventually.

White hair algae are particularly despised in this sense due to their accelerated growth rate and flashy look.

Green algae are at least green, so they look somewhat natural. On the other hand, white hair algae look more like fungus, disrupting the tank’s overall esthetics. And that’s not the only downside, as you will soon see.

So, let’s discuss white hair algae, the underlying causes, and the best treatment and prevention methods to consider.

What is White Hair Algae?

White hair algae are essentially a form of bacteria forming colonies that will spread throughout the tank fast. Matured white hair algae look like cotton or a thick spider web covering pretty much every surface in your tank. This includes plants, aquatic decorations, tank equipment, and, yes, even fish.

Unfortunately, this type of algae will grow fast, faster than your plants. So, it’s easy for them to invade the entire habitat, provided you are oblivious to the problem. Fortunately, there are ways to both remove and prevent white hair algae effectively.

But, first, let’s get into what triggers white hair algae to appear in the first place.

What Causes White Hair Algae in Fish Tank?

There are several triggers that will cause algae bloom in your fish tank.

These include:

Excess Waste

Every fish tank requires regular maintenance to prevent the accumulation of ammonia, nitrites, and nitrates. Normally, you will have several mechanisms in place to keep these chemicals under control.

Your filtration system and the tank’s own natural biofilm will convert ammonia and nitrites into nitrates, which are less harmful to your fish.

Then your plants will feed on nitrates and phosphates, keeping the system in balance. It all sounds fine and dandy until you realize that the aquarium is a closed system. In other words, it cannot remain self-sustainable for too long.

You also need to perform regular fish tank maintenance to remove fish waste, food residues, dead organic matter, and other dangerous chemicals that may seep into the water from various sources.

Skipping the maintenance day too often will give the algae the nutrients they need to bloom. The dirtier the water is, the faster and more aggressively the algae will spread.

Improper Lighting

This is a key point since it has such a major impact on your tank’s stability. You don’t need to be extra thorough about your tank’s lighting if you have no live plants.

Fish will get along just fine with moderate lighting. The situation changes when adding live plants to your tank.

Plants require 8-10 hours of sunlight (or the equivalent) per day to perform proper photosynthesis. The problem is that many people will either keep the light on for too long or go overboard with the light intensity.

Both these problems will contribute to algae formation and bloom because algae love brightly-lit environments.

Not to mention, excessive light will disrupt your plants’ abilities to consume CO2, and the excess CO2 is another algae-producing factor.

CO2 Excess

Live plants require CO2 during the photosynthesis process. They use this component, along with sunlight and various other nutrients, to support their physiological processes and produce oxygen.

This all happens during the daytime. During the nighttime, the plants will consume oxygen and produce CO2 instead.

So, the process is reversed, allowing plants to maintain some type of chemical balance in the tank. The problem is that, as plants grow, they need more CO2.

In this case, CO2 injections may sometimes be necessary based on the plant’s type, growth rate, and overall aquatic setup.

The problem is that plants will consume CO2 at an accelerated rate during the daytime, so it’s easy for them to experience CO2 deficiency over time. This is great news for algae since they thrive in low-CO2-high-oxygen environments.

Overcrowded Tank

Many inexperienced aquarists will crowd their tank with fish, plants, and a variety of decorative elements, looking to create a natural and lush environment.

The problem is that, by doing so, they are oblivious to the risks associated with that behavior.

The more fish you house, the higher the amount of poop they will produce. In turn, these create more ammonia and nitrites than your plants and biofilm can handle.

Overpopulating your tank with plants, on the other hand, will increase the amount of dead matter, especially since plants will compete over the available nutrients. Some will inevitably die as a result.

And finally, overburdening the tank with decorative elements will make it harder for the water to circulate around the environment properly.

The numerous decorations will also hide the fish waste and food residues, creating the ideal breeding ground for bacteria and algae. They will also make cleaning the tank without disturbing the environment more difficult.

Not Removing Algae in Time

This is the final and most important cause of algae bloom. No matter what prevention methods you would embrace, it’s always useful to realize that algae are inevitable.

They will form in any aquarium, no matter how thoroughly you prevent them.

This is where the management strategy comes in. Your goal should be to both prevent algae and cull them once all prevention methods have failed. And they will fail at some point.

That’s because the role of all algae prevention methods is to slow down algae development and spread, not avoid them altogether, since that’s an unrealistic expectation.

How to Get Rid of White Hair Algae?

Given that all of your prevention methods have failed, and hair algae have become visible, it’s time to go to the next step, which refers to removal strategies.

Here’s how you go about that:

Algae Eaters

This is the easiest and most natural strategy since it doesn’t involve chemicals, lowers your involvement level, and diversifies the available fauna. You simply introduce some algae-eating aquatic animals to the tank, and they will take care of your problem.

Some notable mentions here include bristlenose pleco, ghost shrimp, Siamese algae eater, mollies, mystery snail, etc.

The diversity of the available algae eaters is quite impressive, so you will have a large pool at your disposal. Remember that while these animals feed primarily on algae, their diets need to be more diverse. So, you should feed them extra nutrients to make sure that they remain healthy long-term.

That being said, it doesn’t hurt to starve your algae eaters for a couple of days, especially if you’re dealing with a severe algae infestation.

Snails, in particular, will take the starving process as a challenge.

Manual Removal

This one is as simple as it sounds. Your first challenge is identifying the invasive algae because white hair algae are more difficult to spot than other species.

Once you’ve done that, consider removing and cleaning any objects or surfaces housing white hair algae. Some surfaces are easier to clean, while others are not so much.

Make sure not to use tap water when doing so because tap water contains chlorine which is toxic to fish.

If you can’t remove the algae manually, consider other methods instead.

CO2 Injections

As we’ve discussed, plants use CO2 during photosynthesis to produce oxygen and extract proper nutrients from their environment. The problem here is that algae consume oxygen.

So, during the day, plants will consume CO2 and produce oxygen, which can be a problem in tanks with too many plants.

The excess oxygen during the day will contribute to algae formation and bloom. To prevent that, consider adding more CO2 to the tank.

The excess CO2 will work against the algae, preventing them from breathing and killing them shortly. The excess CO2 won’t hurt the plants but actually, help them.

Be careful about your fish, though. Make sure that your fish species can handle the more elevated CO2 levels before committing to it.

Lower Light Intensity and Duration

Algae love light, and they will bloom in brightly-lit habitats. Lowering the light levels will disrupt their physiology and cause them to die shortly.

Make sure that your plants can withstand the lower light levels, though. You don’t want also to kill your plants in the process.

How Do You Prevent White Hair Algae?

This is where the true algae control method comes in. It’s always easier and safer to prevent white hair algae than to counter them once established.

So, here are some good prevention and control methods that everybody should know in relation to white hair algae:

Add Plants

This is a given. Plants are the number one stabilizing element in any aquatic setting. They keep the environment clean, consume phosphates and nitrates, and create natural competition for algae.

They will take up space, light, and nutrients from algae, creating an environment where, at a minimum, they cannot bloom.

Naturally, adding plants isn’t enough, but it’s the first method you should employ.

Regular Maintenance

You should never skip maintenance day. How frequently you should engage in cleaning and maintenance depends on a lot of factors, such as:

  • How many fish do you have
  • How much waste they produce (goldfish and cichlids are notorious waste-producing species, for instance)
  • How large the tank is since smaller tanks require more frequent cleaning
  • How much food does your fish get because overfeeding them will create more waste, etc.

Ideally, you should clean your tank at least once per week. Some aquariums may need more frequent cleaning, based on the factors I’ve just mentioned.

Doing so will eliminate the excess ammonia and nitrites and minimize phosphates and nitrates, contributing to algae formation.

Manage Liquid Fertilization Carefully

This point ties closely to the previous one. Liquid fertilizers are necessary for floating plants because these have no roots, so they cannot feed from the substrate. Instead, they will process their nutrients straight from the water around them.

The problem is that using too much liquid fertilizer will create an imbalance between what plants need and what they’re getting.

The excess nutrients will feed the mass of algae waiting to bloom and take over. Only provide your plants with what they need, and be careful about any excess. Nothing will go to waste. If plants can’t consume the available fertilizer, algae will, and you clearly don’t want that.

Manage Light Intensity and Duration

All plants require sunlight (or the equivalent in LED lighting) to perform proper photosynthesis.

The problem is that different plants require different levels of lighting. For instance, Java fern and java moss don’t need as much lighting as other plant species.

White hair algae will bloom if the light is too bright or you don’t have a stable day/night cycle. Other algae species might show up as well, causing additional problems for you to handle.

Rely On Algae Eaters

This should be a given in any aquatic system. Algae eaters are pretty much necessary in every aquarium since they make up the cleaning crew.

Whether you prefer fish, snails, or shrimp, it’s important to have at least one species of algae eaters around.

These will consume the algae while they’re still young, preventing them from taking over the tank.

In essence, it’s relatively easy to control the algae population and prevent its spread. It all comes down to being aware of the risks and triggers and figuring out the best prevention methods.

What Eats White Hair Algae?

A multitude of aquatic creatures will consume white hair algae. These include fish species like the Siamese algae eater, bristlenose pleco, otocinclus catfish, cherry and amano shrimps, nerite snails, etc.

Snails, in particular, are extremely effective at combating white hair algae and other algae species.

They will graze all day, consuming as many algae as possible. Just make sure your snail population doesn’t get out of hand, which tends to happen in environments rich in nutrients.

Is White Hair Algae Dangerous to Fish?

Yes, white hair algae is dangerous to fish, both directly and indirectly.

Here’s what I mean by that:

Blocking Light

White hair algae will spread everywhere and cover every surface, which is typical algae behavior. This will lead cause the plants to no longer receive the adequate light levels necessary for photosynthesis.

As a result, plants will become less effective at maintaining the chemical balance in the water and oxygenating the environment.

This will affect the fish directly. You can tell that your fish begin to have difficulties breathing or experience ammonia poisoning relatively soon into your algae bloom problem.

Most fish will experience erratic swimming, gasping for air in the upper portions of the tank where the levels of dissolved oxygen are higher, and experience low appetite.

If your algae infestation is severe, your plants will begin to die off.

Nutrient Competition

This is another point that defines the relationship between algae and plants. White hair algae and plants compete over the same nutrients, pretty much.

This is why adding plants to the environment controls the algae population by starving them. The same thing happens when algae take over.

Your plants will no longer have access to the same amount of nutrients which will have disastrous consequences over time. Again, this will affect your fish as your plants begin to die.

The excess dead plant matter will further feed the algae population and increase the levels of ammonia, poisoning all aquatic life in the process.

Entangling Fish

This is a more advanced problem, typically relating to excessive algae development. White hair algae grow in long strings and can become quite thick when mature.

Fish can easily become entangled in them, which can lead to death via asphyxiation. Fish need water movement to oxygenate themselves properly.

Fortunately, this problem is only typical to extreme algae infestation. It’s unlikely that you will allow the problem to get to this point. But it’s worth being aware of the risks.

As you can tell, white hair algae aren’t exactly easy to ignore. These organisms aren’t harmful when moderated.

They are actually quite welcomed in the environment since they serve as food for your fish. It’s the unhinged algae development that should concern you.

Will Flourish Excel Kill White Hair Algae?

First, as a disclaimer, I should mention that the scientific community (read ‘forum people’) are divided on this issue. So, most of the evidence comes by means of anecdotal evidence.

Even so, most people have reported that Flourish Excel cleaned their algae tank soon after use.

That’s most likely because Flourish Excel contains glutaraldehyde. This chemical has vast applicability in medicine and has uses in many other areas, including plant control.

In other words, glutaraldehyde functions as a herbicide and is considered among the most potent algae killers.

So, yes, Flourish Excel is quite effective at removing algae from your tank. Other products that contain glutaraldehyde may also be useful in this sense.

What matters here is the concentration of glutaraldehyde and how much solution you’re using.

Use too much, and it may also kill your plants. Always stick to the user instructions present on the product’s label to prevent that.


As we’ve already discussed, white hair algae are quite common in any aquatic setup. Fortunately, you have a variety of algae-removing tools available to cope with your algae problem.

I hope this article has shed light on how to counter white hair algae and prevent their spread more effectively.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.
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