This is how you prevent your tank from getting black beard algae

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Many different forms of algae can grow in aquariums, spoiling the look of your setup, clogging filters, and obscuring the glass. Black beard algae are a particular nuisance because they are unsightly and very difficult to get rid of.

This article will tell you everything you need to know about removing black beard algae from your tank.

What are black bearded algae?

Blackbeard algae are extremely tough algae that can be difficult to remove. The algae grow on the leaf edges of slow growing plants such as Java fern and anubia. Once attached to the leaves, the algae are incredibly difficult to completely move. In severe cases, the algae block the plant’s access to light and food and ultimately kill it.

You will also see black beard algae growing on aquarium equipment, decorations, bog wood, stones, and even grains of gravel in the substrate.

Black beard algae are also known as brush algae. The scientific name of the organism is Audouinella and belongs to the red algae family. The natural color of the algae varies from very dark green to gray to deep black. The algae grow in furry tufts that resemble a beard or a brush, hence the organism’s common name.

What causes black beard algae?

Black beard algae can have a number of causes including excessive light in the tank, low or fluctuating CO2 levels, high levels of pollutants in the water, and lots of debris floating in the tank.

However, the main cause of black beard algae outbreaks is low or unstable carbon dioxide levels in the water. How come? If the CO2 level is unstable or very low, living plants in the aquarium cannot use the light and nitrate fertilizers available for photosynthesis. Unfortunately, while this type of environment is bad news for plants, it’s great for bearded algae.

Too much light

Like most plants and algae, black beard algae thrive when exposed to plenty of light. The more light the organism receives, the faster it spreads.

The longer you leave your tank lights on, the more algae will grow. A quick fix is ​​to reduce the amount of time light falls on your aquarium. By depriving the algae of light, you can stop their growth or even eliminate it altogether if you use this tactic in combination with other eradication methods.

Try a reliable aquarium timer that will automatically turn your lights off and on again every day so you don’t have to remember.

How do blackbeard algae get into the tank?

Black beard algae get into your aquarium in two ways. You can buy some new plants and add them to your setup without knowing that they have tiny blackbeard algae spores that are invisible to the naked eye. These spores develop into algae, which then become visible and spread throughout the tank under the right conditions.

Blackbeard algae can also enter your aquarium as tiny, free-floating strands in a bag with new fish. In the tank, the algae attach themselves to a suitable surface and grow.

Are Black Beard Algae Bad For Your Fish?

Black bearded algae are not harmful to fish. In fact, many fish seem to like to hide under the flowing mass of algae. Some aquarists actually encourage black beard algae to grow on certain rocks and pieces of driftwood, as these can look very attractive with proper care and control.

How to remove black beard algae

While it is undoubtedly difficult to get rid of blackbeard algae, it is possible to move it and there are several ways to do it.

Pruning plants

The most effective way to remove black beard algae from plants is to remove infected leaves by cutting them off with aquasaping scissors.

Clean decorations

You can remove the worst black beard algae from solid objects in the aquarium by removing the organism with an old toothbrush or wire brush. As you work, use a siphon to remove any debris and algae that you remove so they don’t swim away and infect other parts of the tank.

Algae that cling to the glass can sometimes be moved around with a razor blade or plastic scraper. Again, make sure to vacuum off the algae and debris while you work and make sure that the silicone seals are not damaged.

Bleach stones and decorations

You can remove any infected stones and decorations from the tank and soak them in a bleach solution for a few minutes. Scrub the items to remove the algae before rinsing them thoroughly and placing them back in the tank.

Paint the seaweed

Another way to deal with black beard algae is to lower the water level below the algae growth. So if an algae outbreak is growing on a rock, you can remove enough water from your tank to expose the algae to the air.

Measure out your usual daily dose of Seachem Flourish Excel, but instead of pouring it into your tank, take a very small paintbrush and brush the undiluted liquid onto the algae affected areas. Leave the algae exposed for about a minute, then refill the tank as you would during your weekly water change.

After a day or two, the black beard algae should turn pink and die off. In this case, use a brush to remove as much residue as possible.

Add algae eaters to your tank

You can let nature do the work by adding some algae eaters to your tank. Unfortunately, only a few fish eat blackbeard algae, including the Siamese algae eater (Crossocheilus siamensis) and the Florida flag fish. Make sure you are buying the right type. Many fish are sold under the Siamese algae eater name, but are actually a different species.

Shrimp also eat algae and graze on black beard algae. However, shrimp usually don’t eat fast enough to really affect the algae ‘s progress.

The main disadvantage of using algae eaters to control algae in your aquarium is that there is no guarantee that the creatures will actually eat the algae!

Treat the tank with copper

If all other efforts to get rid of blackbeard algae fail, you can treat the tank with copper, carefully following the manufacturer’s instructions. However, copper can damage some plants, fish, and invertebrates and must be used with caution.

Prevention of black beard algae

Now that you know how to identify and treat blackbeard algae, let’s talk about how to keep them from infesting your tank in the first place.

New plants

Never take plants from one tank containing algae and transfer them to another tank free of algae.

When buying new plants, soak them in a 10% bleach solution in conditioned tap water for two to three minutes to kill algae before adding them to your tank.

New fish

Before placing new fish in your exhibition container, we recommend that you quarantine them. That way, you can monitor your new acquisitions to make sure they are disease free and healthy. If blackbeard algae are in the water the new fish got in, they will be trapped in the quarantine tank instead of ruining your display tank.

Whenever you transfer the fish to your main tank, always use a net so that water gets into the setup now.

Improve water quality

Poor water quality encourages black beard algae to grow and is very bad for your fish and other animals.

Perform a 25% water change weekly, flush the filter media in tank water every month to remove clogs and sludge, and change the used filter media as necessary. Vacuum the aquarium substrate weekly to remove debris and debris, and regularly monitor the pH of the water to avoid an overly acidic environment.

Increase the CO2 level

You can help keep the tank environment unattractive to black beard algae by adding liquid carbon to the water every day. A good product for this purpose is Seachem Flourish Excel.


Blackbeard algae are an unsightly threat that can quickly ruin your tank by attaching themselves to plants and decorations. While it is possible to get rid of blackbeard algae using one or more of the methods described above, it is best to avoid the problem first.

Keep your aquarium clean and hygienic, be careful when introducing new plants and fish, and don’t give your aquarium too much light.

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