Black Beard Algae: Treatment, Removal, Cause & More

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What is Black Beard Algae?

Black Beard Algae (Audouinella sp.) is a common type of algae that grow in aquariums. It belongs to the red algae family and it is also known as brush algae, black brush algae, or sometimes just by the initials BBA. If you have algae in your tank, there’s a good chance that it’s Black Beard Algae.

Black Beard Algae often grow on the leaves of slow growing aquarium plants, but it can grow on almost any surface in the aquarium. It is made up of very fine strands or tufts of dense patches. It resembles a beard, which is how it earned its name. It often has black coloration, but it can show up as bright green, blue green, or blackish green. It starts off as a small patch of short fibers, but they will quickly grow longer if left unchecked. It will typically start to grow on the edges of plant leaves, but it will eventually cover the whole leaf.

Black Beard Algae doesn’t release toxins in the water, or steal nutrients from plants. However, it can kill the plant if it completely covers the plant. When the plant is covered, it would not be able to absorb the light for photosynthesis. Too much Black Beard Algae can also lead to imbalances in your water, and make it an unsafe environment for fish in the affected aquarium.

If you spot a small amount of Black Beard Algae in your tank, it may not be a big problem initially. However, the issue should be addressed before it becomes a larger problem. It can take over an aquarium if it is left unchecked and it is nearly impossible to manually remove it. Not to mention, they are very unsightly as well.

Black Beard Algae

What Causes Black Beard Algae Growth?

The primary causes of Black Beard Algae is too much light, too much nutrients, or low CO2 levels in your aquarium.

The Black Beard Algae may be introduced into the aquarium through contaminated substrate, rock, or driftwood. Therefore, properly cleaning these items before adding it to the tank is important. When new fish and plants are added to the aquarium, some of the water that comes with it could contain strands of Black Beard Algae as well. A quarantine period of at least 2 weeks is recommended.

It doesn’t take a lot for you tank to get contaminated. Since it is an algae that occur abundantly in nature, there is a high chance that your aquarium will be exposed to it regularly.

Preventing exposure to Black Beard Algae completely may be difficult. Therefore, the key is to understand what causes it to grow, and prevent that from happening. Here are the primary causes of Black Beard Algae growth:

Too Much Aquarium Light

Black Beard Algae often grows when there is an excess of aquarium lighting. When there is a high intensity or long duration of light, it often thrives and grows very quickly. If the tank is exposed to direct sunlight, it may be a good idea to move the tank or block the direct sunlight with a shade. In order to control the duration of light that the aquarium receives, installing a light timer may be a good idea. Reducing the number of hours that the aquarium receives may slow the growth rate of the algae, or even stop its growth completely. If the aquarium receives 12 hours of light per day, consider gradually reducing it to 8 hours of light per day.

Too Much Nutrients

Black Beard Algae often grow when there is an excess of nutrients in the water, such as nitrates. There are several factors to consider when controlling the level of nutrients in the tank. First, consider reducing the amount of available nutrients for the algae by doing regular water changes. Second, make sure that the fish are not overfed. If the fish are overfed, they would be producing a lot of waste. Even if the fish are not overfed, the tank could be overstocked as well.

Low CO2

Low CO2 levels or unstable CO2 levels can result in Black Beard Algae growth. By increasing and stabilizing the CO2 levels in the tank, the aquarium plants will be able to absorb more nutrients in the water. It will be able to compete with the algae more aggressively. Fast growing stem plants such as Hornwort and Anacharis are awesome plants that will absorb nutrients very quickly. Fast growing floating plants such as Duckweed and Amazon Frogbit can be great as well, since they are able to reduce the light intensity in the tank as well.

CO2 levels in your tank can be increased with an aquarium CO2 system. CO2 levels of up to 15-25 mg/L can be added to aquariums.

Providing an adequate amount of water flow within the tank may stabilize the aquarium environment, resulting in less Black Beard Algae growth as well.

Fish that Eat Black Beard Algae

A natural way of controlling Black Beard Algae is to let the fish eat them. Some fish eat algae as their primary food source. Other fish will eat algae as a part of their varied diet. Either way, this is great because the fish will have something to graze on throughout the day. Not to mention, it is a free food source.

Here are some fish that may eat Black Beard Algae:

While they aren’t fish, invertebrates such as snails and shrimps can help control Black Beard Algae as well.

Here are some invertebrates that will eat Black Beard Algae:

Keep in mind that many fish and invertebrates will graze on the Black Beard Algae, but they may not eat all of it. While some fish will constantly work at it, other fish may only occasionally nibble at the algae. Black Beard Algae is difficult to eat for many fish, and many that are well-fed will not bother eating the tough Black Beard Algae.

Black Beard Algae Treatment and Removal

It is possible to use treatment to remove Black Beard Algae. By using proper treatments methods, it is possible to get rid of them safely and effectively. Some of the options of treating Black Beard Algae are Hydrogen Peroxide and Flourish Excel.

Hydrogen Peroxide for Black Beard Algae

Hydrogen Peroxide is an effective way to treat Black Beard Algae. It can be purchased over the counter at most drugstores, and is a great thing to keep handy for aquarium owners.

If you suspect your plants, decorations, or aquarium equipment have Black Beard Algae, you can take them out and soak them in a bath of three percent Hydrogen Peroxide for around three minutes. After the three minutes is up, you simply just rinse everything off thoroughly in freshwater to remove the Hydrogen Peroxide.

If removing the affected items is not an option for you, you can treat your whole tank with Hydrogen Peroxide. Use 10mls of three percent Hydrogen Peroxide per 15 gallons in your tank. You can add the Hydrogen Peroxide to your tank by the pump so that it gets evenly distributed through your tank. Within a few days, you should notice the Black Beard Algae in your tank beginning to fade in color. It should die off in a month or so. Even if it does not resolve the issue the first time, it is safe to repeat this process over again. If the algae is stubborn, and not dying off, you may consider using a slightly higher dosage.

During this process, you may notice some of your plants changing color. Usually, the plants should return back to normal after some time. Hydrogen Peroxide shouldn’t affect the fish in your aquarium, but you can remove them from the tank during treatment.

Flourish Excel for Black Beard Algae

The main compound of Flourish Excel (Glutaraldehyde) is used in the agriculture industry as pesticide, and it is used to disinfect and sterilize heat-sensitive equipment. Using Flourish Excel can be another method of removing Black Beard Algae from your aquarium. Flourish Excel is basically liquid carbon, and is a good alternative that has a similar effect to CO2 injections.

CO2 helps plants absorb nutrients more effectively. To use Flourish Excel in your tank, you basically have to overdose the tank to treat it. However, overdosing your aquarium with Flourish Excel could potentially be harmful to your fish, and kill off your more sensitive aquarium plants. Using treatment solution requires careful consideration of all risks and understanding proper use. It is important to refer to the manufacturer’s instructions as well.

What to Consider When Using Flourish Excel for Black Beard Algae

Water Volume of Your Tank

It is important to know the exact water volume of your tank, so that you know how much to put into your aquarium. This is especially true if you have a small tank, since the ecosystem in small environments are very fragile. You may want to start with a dose slightly under the recommended amount for a smaller tank.

Types and Amount of Plants

The right amount of Flourish Excel to use may be different, depending on the amount of plants that are in your tank. For aquariums with few plants, the recommended dose may kill the plants. However, for a heavily planted setup, you may need to use more. This can it difficult to determining the right amount of Flourish Excel to use.

Aquarium Lighting

If the aquarium is exposed to a lot of light, the algae may continue to grow even if the Flourish Excel treatment. Therefore, consider adjusting the hours of light that the aquarium receives by using a timer. It is generally not recommend to keep the light on for more than 10 hours a day if you are trying to control algae growth.

Understanding proper treatment methods is important for safety and efficacy. Be sure to refer to the manufacturer’s instruction before administering the treatment.

API Algaefix for Black Beard Algae

Unfortunately, API Algaefix is generally ineffective against Black Beard Algae. API Algaefix works on simple green algae such as green water. However, Black Beard Algae belongs to the red algae family, so this wouldn’t be the most effective treatment option.

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With decades of collective fishkeeping experience, we are happy to share the fish care tips that we've picked up along the way. Our goal at Fish Laboratory is to keep publishing accurate content to help fishkeepers keep their fish and aquarium healthy.

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