Brown Hair Algae in Freshwater & Saltwater Aquariums

So you’ve got this beautiful aquarium in the corner of your house. And every time you walk by, the vibrant fish swimming around with absolute glee makes you very happy. But on your last few walks, you noticed the walls of the aquarium to be a bit fuzzy. You think the water is getting muddy, and it’s time for the weekly cleanse. So you clean the tank, change the water as usual, and continue your day.


The most common causes for brown hair algae in freshwater and saltwater aquariums are excess silica and an abundance of nutrients at the bottom of the tank. The best treatment for brown hair algae in freshwater and saltwater aquariums is getting algae eaters and cleaning it off.

We’ll also cover the following topics in more detail:

  • What it is
  • Whether it’s harmful
  • Whether it goes away by itself

Continue reading

brown hair algae

Strolling around your house again, you notice that your aquarium still appears foggy. You squint and take a closer look at the insides of the tank and notice a brown hair-like substance covering the plants and a bunch of other surfaces in your tank. You realize that this brown hair-like stuff is making the aquarium appear dusty from afar. You quickly google and find out that this stuff is called Brown Hair Algae, whose appearance in tanks is quite common, and land on this article. Keep reading to learn more about the algae, why it has appeared, and what you can do about it!

What is Brown Hair Algae in Freshwater & Saltwater Aquariums?

Brown Hair is algae that belong to a group of Algae called Phaeophyta Phylum (scientific name) that most tank owners are likely to come across at one time or another. These Brown Hair Algae are diatoms that photosynthesize light into energy. They’ll start as single-celled organisms, visible only at a microscopic level. Once they start developing, they like to attach themselves to a surface and expand in clusters. These clusters take the shape of brown filaments that mimic the appearance of brown human hair. Thus, it’s its name!

Why does it keep appearing?

Now that you’ve identified the substance that’s made your stunning aquarium appear like a filthy mess, it’s time to figure out why. Why are this algae growing in your aquarium, and is it here to stay? Will it harm your plants and fish, or are they just part of the ecosystem you’ve created? Let’s get to answering those questions right away.

Firstly there could be several reasons for Brown hair algae growing in your tank:

Excess Silica

The diatoms we were talking about earlier can exist on their own or form clusters and expand. Usually, they use silica to create protective shells around themselves and multiply rapidly. Silica is present in all aquatic environments, and excess can make Brown Hair Algae persist rapidly. Excess silica could be a result of the following:

Water Quality:

If you have a freshwater aquarium, chances are you’re relying on tap water for its maintenance. However, tap water can be high in silicic acid and thus result in the growth of Brown Hair Algae.

Silica Sand:

Silica sand is the sand used at the bottom of the aquarium. It makes the whole aquarium environment look more realistic. Often, you may pick it up with the tank, not sure what it’s truly made of. Silica Sand causes high silica in the tank’s environment for the Brown Algae to feed on and thrive, so make sure to find a substitute.

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Excess Nitrates

Other than Silica, Algae also feeds on excess nitrates, which helps it thrive in your aquarium. What is Nitrate? Fish waste, unconsumed and decayed fish food, and dead animal or plants are converted into nitrates through a chemical process. You can easily prohibit nitrates in your tank water with regular cleaning.

Excess Lighting

Another often overlooked factor resulting in brisk Algae growth is excess lighting. Most of the time, the fish and the plants don’t require much lighting to living and thrive. Although the lighting depends on the specific species of your plants and animals, usually, they don’t need as much. If you think about it, these organisms survive in the ocean’s depths, where light is often dainty.

Algae flourish more than plants and animals when aquariums are given too much intense lighting over a long period. So if you’re lighting your aquarium intensely for aesthetic reasons, you might want to dial it down.

Poor Water Quality Overall

Suppose you’ve got optimum levels of lighting and silica in your tank. Even then, the healthy aquatic environment of your tank can still easily be thrown off by delayed tank cleaning or poor-quality water. You should use RO (reverse osmosis) water in a tank with excess nitrates and silica and clean them out at regular intervals. The intervals at which you should clean your aquarium depend on the number of plants and fish you house.

Is it harmful?

Brown Algae, in its initial spotting, isn’t as harmful. Since you’ve just noticed it, it probably hasn’t spread wide enough to cause any damage to your plants and fish. However, gone unnoticed, it can spread its clusters and cover your plants entirely. When brown hair algae cover plants, it restricts their access to light, which hinders their ability to carry out photosynthesis. Since photosynthesis is the process of converting light into energy, the inability to photosynthesize will cause them to starve and die. Dead plants will immediately affect the oxygen level in your tank, directly impacting the fish. So, if you don’t want things to get this bad, we suggest you prohibit their growth in the initial stages.

Will it go away on its own?

The growth of Brown Hair Algae can be hampered if you cut down its supply of silica, nitrates, or excess light. However, it won’t go away entirely and will continue to spread slowly. If you’d like to get rid of Brown Hair Algae from your tank, you’d have to take appropriate measures to do so.

How do I get rid of it?

Clean it off.

Well, the first thing you’ll have to do is remove it by cleaning your tank. Yes, we mean manually. Unlike other algae species, Brown Hair Algae don’t attach themselves firmly to any surface. So they’re fairly easy to wipe away with a sponge or cloth. After you’re done wiping it down, suspended particles might still float around in the aquarium. It’s best to use a vacuum to suck these. If you have a good filtration system installed, it’ll draw the algae into its system automatically.

Get algae eaters

Although it doesn’t strike immediately, getting fish that like to feed on algae is the most natural and efficient way to keep your aquariums clean. The only problem is that not all fish species are compatible with algae-eating species. Many fish species are incompatible with living with each other due to different water requirements. Keeping this in mind, we’ve created a list of a few best algae-eating species that can thrive in saltwater or freshwater aquariums:

Algae eaters that live in FreshwaterAlgae eaters that live in Saltwater
Reticulated Hillstream LoachNerite Snails
Cherry ShrimpMolly Fish
Otocinclus CatfishAtlantic Blue Tang
Siamese Algae-eaterSailfin Tang (Pacific)
Rosy BarbScribbled Rabbitfish

In freshwater aquarium

Though saltwater tanks have many more options, do not underestimate the useful variety of species that bloom in a freshwater aquarium. There’s the Suckermouth, the Octocinclus, and the cute Rosy Barb can be a beneficial addition to your aquarium.

In saltwater tanks

Most saltwater tanks are filled with an array of colorful fish. That’s why people opt for them in the first place. When it comes to saltwater tanks, there’s a wider array of livestock to choose from as compared to fresh water. However, we suggest you also pick some useful species rather than those that look colorful and appealing. The nerite snail, for example, may look small, sitting in the corner of your aquarium. Still, it’s a useful buddy to have around when it comes to eating algae.

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Liquid Volume55 Gallons
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How to Prevent it in the First Place?

So, you’re done removing the algae, but now what? How do you stop it from coming back? If you’ve figured out why your aquarium had the Brown algae in the first place, it’ll be fairly easy for you to guess what to do next. But suppose you’re not sure why Brown Algae showed up in the first place. In this case, we’ve listed out all the preventative measures you can take to keep nitrates and silica at bay. Of course, keep the overall environment of your little ecosystem healthy! Here they are:

Clean your tank daily.

It might initially look like a hectic task since we’re asking you to clean daily. However, you will take hardly five minutes to do this task every day. Plus, it’ll save you from running larger, more time-consuming errands if the Algae shows up again. Cleaning your tank just means removing uneaten fish food and fish food from the bottom of the tank.

Use Reverse Osmosis water.

Tap water can have an excess amount of nitrates, silicic acid, and many other substances that can make it difficult for you to control the environment of your aquarium. It is recommended you use RO water to fill your tank instead.

Maintain a schedule for changing the water.

In aquariums, regardless of the size of the fish, their housing need at least 15 to 25% of their water changed regularly. Although smaller tanks indeed need their water changed more frequently than bigger ones because dirt and nitrates tend to build up faster in smaller tanks. Some fish are also messier than others, so figure out a schedule that maintains the mineral balance of your aquarium and stick to it.


Brown hair algae is a very common and natural phenomenon that occurs when the chemical balance of your aquarium falls off the edge. It is why following preventative measures to keep your aquarium clean and healthy is the only way to go. There is no permanent solution to getting rid of Brown hair algae once and for all. So, keep an eye out for any Brown-Hair Algae because early detection also means timely treatment.

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