Brown Hair Algae: How To Manage Them?

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Hair algae in general are prolific species. With the right conditions, they will grow and rapidly multiply.

I personally experienced the hair algae’s fertile behavior after I came back from a month-long vacation. Before I left the house, my 20-gallon tank was aesthetically beautiful with the splendid greenery of live aquatic plants. But when I arrived, it was a carpet of mess full of unpleasant coffee-colored bushy outcroppings.

Brown hair algae took over and dominated my tank.

I did not plant them and they just grew naturally.

Brown Hair Algae

What should I do?

Join us in this article as we discover what brown hair algae are, why they proliferate and learn ways to get rid of them.

Taxonomic Classification of Brown Hair Algae

Categorized under Phylum Phaeophyta, brown hair algae are diatoms which is a type of photosynthesizing algae.

They start out as a microscopic free-swimming single-celled organism with a yellow-green to brown in color. As they develop, they cling to a hard object and form clusters of filaments that look like a hair, thus its name.

The carpet-like growth of their filaments is the reason why they cover and wrap live aquatic plants, decorations, glass and sand.

Fun fact: Did you know that giant kelp is the largest member in Phylum Phaeophyta and the largest algae in the world? Thriving in a cold-water ecosystem, giant kelp can grow up to 70 meters (230 feet) long and their growth forms dense underwater forest.

Silica: The Primary Cause of Brown Hair Algae Proliferation

The unicellular cells of brown hair algae are unique. These microorganisms have the capability to absorb silica in the water.

In the form of dissolved silica, brown hair algae use these compounds to form a glass shell. This outer layer of protection for each brown hair algae cell is called a frustule. When frustules group together, they form a filament which is now visible to the naked eye.

Fun fact: Do you know that when brown hair algae die in the wild, they settle in the bottom and fossilize into diatomite that forms into a new sedimentary rock?

Formation and Sources of Silica in the Tank

You may wonder how silica is formed and what are their sources.

Surprisingly, silica is abundant in nature, especially in the aquatic ecosystem. Also called as silicon dioxide (SiO2), silica is formed when oxygen and silicon are mixed together.

Aside from the glass itself, the source of silicon in a tank setup comes primarily from rocks and sand. When this common bed material comes in contact with dissolved oxygen, they form silicon dioxide, which is then used by the frustule development in brown hair algae.

The higher the silica content, the faster brown hair algae will propagate.

This is the reason why a newly set-up tank is prone to brown hair algae infestation. The addition of new rocks and sand in a new tank means that you have a fresh supply of silicon and it may take time to stabilize as they are being absorbed by plants and the algae themselves.

Supplemental Causes of Brown Hair Algae Proliferation

Aside from the presence of dissolved silica, brown hair algae will bloom and take over your tank if certain conditions are met.

  • Excessive Nitrates. Despite being a by-product of fish waste, nitrates are considered food for the brown hair algae.

When you have a poor filtration system, ammonia and nitrites are accumulated in the water column. When this happens, microscopic nitrifying bacteria will convert them into nitrates. In effect, nitrates facilitate the fast blooming of brown hair algae.

  • Presence of Strong Light. Most of the common fish and aquatic plants really don’t need too much lighting. However, considering the aesthetic effects it brings, we usually put strong bright lights to our tank.

With the presence of bright light, it facilitates photosynthetic activity and allows rapid growth of brown hair algae.

Cleaning a Brown Hair Algae Infested Tank

If your tank is infested with brown hair algae, your next step should be a total tank clean up.

  • Remove the Fish. Although fish are not directly affected with brown hair algae, it is best to remove them from the tank and transfer them in a temporary container.

Aside from providing space, your fish will not be exposed to stirred debris as you work your way during the clean-up.

  • Take out live aquatic plants. In most instances, the bulk of the encrusting growth of brown hair algae occurs in live aquatic plants. They are the most affected residents in your tank. Brown hair algae hinders their photosynthetic activity as they cover and block light.

It is best that you take out live aquatic plants from the tank. In this way, you can completely remove brown hair algae by hand. Rinse your plants before placing them back in the tank.

  • Total water change. In the event of a brown hair algae infestation, you can expect that your water is also blooming with microscopic diatoms.

If you don’t completely change the water, then most probably you will start your newly cleaned tank with a number of diatoms. This will become the new generation of filaments of brown hair algae.

  • Clean the substrate. If the infestation of brown hair algae in the substrate is mild, you can do a suction clean up during water change. In this way, you save time and effort as you simultaneously remove the algae and the contaminated water at the same time.

However, if the brown hair algae have a dense cover, then you need to remove the substrate. Once removed, manually pick out the brown hair algae and rinse the substrate before placing them back in the tank.

Important: Do not replace your old rock or sand with a new one. Otherwise, you will be introducing a fresh source of silicon which will become silica and fuel up the development of diatom frustules.

Prevention of Brown Hair Algae Proliferation

Cleaning a brown hair algae infested tank takes time and effort. It is laborious. But it doesn’t mean that nothing can be done to prevent its proliferation.

Here are some preventive measures that impedes the proliferation of brown hair algae:

  • Frequent partial water change. When you have a new tank, don’t wait for a brown hair algae infestation to occur and do a total tank clean up. Instead, perform a weekly partial water change. A 25 to 30% water change will do.

This frequency may change according to your tank needs. But in general, the smaller your tank, the more frequently you should change your water. The reason for this is that organic substances like ammonia and nitrites build up faster in smaller environments.

  • Improve your filtration system. The best way to catch and remove brown hair algae is when they are still in their microscopic single-cell stage. During this time, they are still floating and free-living and the chances of being siphoned in the filter is high.

On the other hand, if you don’t have a filtration system at the start, their free-living state allows them to extract silica, develop their frustules and become filamentous. By this time, they are already attached to a surface and removing them by filtration is impossible.

  • Introducing an algae consumer. It is recommended that you introduce algae-eating organisms right at the start of your tank operation.

In this way, their minute appetite is sufficient enough to slowly control an algae outbreak. You have to remember that introducing an algae-eating organism during a full algae bloom may be too late as they have little impact in controlling their proliferation.

Here are some algae consumers that are proven effective in eating algae. And by the way, they will also eat other species of algae and not just brown hair algae.

  • Suckermouth catfish (Hypostomus plecostomus). Popularly called the pleco, this armored catfish has an inferior mouth with round lips that forms a sucking disc.

They have a large appetite for fiber. This is the reason why they prefer the biofilm and algae filaments. Plecos will graze in almost all areas in the aquarium, like the substrate, decorations and the tank glass itself.

  • Pygmy suckermouth (Otocinclus vittatus). This species of suckermouth fish is a close relative of the plecos. Belonging to the same catfish family, pygmy suckermouth passively eats algae as they graze along the substrate.
  • Amano shrimp (Caridina multidentata). In general, being a detritus feeder, shrimps are natural algae-eaters. However, when it comes to the most effective against algae, nothing beats the Amano shrimp.

Although they only measure 2 inches (5 cm) long, they have a big appetite for algae. Since they are highly mobile, they can go on top of plants devouring most types of hair algae and string algae.

  • Nerite snail. Despite being a slow-moving gastropod, they are fast when it comes to eating algae.

This group of small to mid-sized snails are grouped according to ecosystem: freshwater and saltwater species. So, be mindful to ask and purchase the right nerite snail that corresponds to your tank set-up.

  • Remove while small and few. Don’t wait for the filaments to grow and multiply before you do a clean-up. While it is impossible to eradicate all forms of algae in the tank, controlling their growth and population would really prevent a full bloom.

With the use of a suction tube, gently vacuum out the areas with obvious algae growth. In this way, a part of the algae will be dislodged and their diatomic single-cells will also be vacuumed out.

  • Addition of more live aquatic plants. Brown hair algae are very efficient in using up the water’s nutrients for their growth and development. However, it will be a different scenario when they have a competitor.

Live aquatic plants are an algae’s competitor for nutrients. This means that brown algae will not solely get the nutrients and their growth will be limited.

  • Apply an anti-algae solution. There are a lot of anti-algae solutions that you can choose and use. With just a few drops, algae bloom and proliferation is controlled.

Similarly, you can apply aquatic plant booster. This will enhance the health of your aquatic plants and combat the infestation of brown hair algae.

The Domino Effects of Brown Hair Algae Infestation

The beauty of your tank will surely be compromised if there is a brown hair algae infestation. That’s very alarming, especially for those who are into aesthetics.

But what if you don’t have time to clean your tank and allow the infestation to continue? You should be aware that the bad aesthetic effects of brown hair algae is only superficial.

Our real concern for an infestation is the domino effect.

When brown hair algae start to encrust your live aquatic plants, it will deprive it of its photosynthetic activity. Your aquatic plants may die.

Once your plants die, expect that your dissolved oxygen level will decrease. This is the part where your fish is affected and the chances of dying is highly possible.



With the presence of sand in your tank and as the primary source of silicon, the growth and development of brown hair algae is inevitable. But it does not mean that you have to get rid of the sand just to prevent brown hair algae growth.

Microscopic single-celled diatoms are always present in the water. Take a drop of water, examine it under a microscope and you will be surprised to see how many they are.

What is important for us is for them not to develop into filaments that will directly affect your aquatic plants. And fortunately, preventing the development of algae filaments is easy to manage.

With the steps we just enumerated above, we can guarantee that an outbreak will not happen. So, in effect, instead of spending time and effort cleaning an algae infested tank, you can sit back, relax and enjoy the beauty of your aquarium.

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