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black beard algae

How to Get Rid of Black Beard Algae in the Fish Tank

Written by: Tammy (@aquarist_tland Team Buce Plant


Have you ever encountered this ugly black fuzz growing on the tips of plant leaves or on your aquarium’s hardscape? If so, it's most likely Black Beard Algae (BBA), also known as Black Brush Algae. Out of the many types of algae that we see in freshwater fishkeeping, black algae in the fish tank is arguably one of the most stubborn to remove...but don't get discouraged!

Although it can be somewhat troublesome to get rid of, it is not impossible.

In this article, we’ll answer:

1. What exactly is Black Beard Algae?
2. What causes Black Beard Algae?
3. Is BBA harmful?
4. How do I get rid of BBA?
5. How do I prevent BBA?

 black beard algae

What Exactly is BBA?

Audouinella is the scientific name for black algae. It’s a genus of red algae that exists in both freshwater and saltwater environments. The form of Audouinella that we encounter in the aquarist hobby is commonly referred to as “black beard algae,” “black brush algae,” "black algae," or “BBA” for short.

They look like dark patches of hair and typically grow on the edges of leaves, driftwood, stones, or other types of decoration. Contrary to its given name, black algae can either be black, dark green, or dark red in color. BBA likes to grow in areas of high flow, but can also be found in areas with low circulation.


What Causes Black Beard Algae?

Like all other algae, the main reason BBA grows is because of an imbalance in the aquarium. This imbalance is most likely due to an abundance of nutrients. The black algae will take advantage of the surplus of nutrients and utilize them to grow and spread throughout the tank. Black Beard Algae can be a result of poor water quality, poor maintenance, overdosing fertilizers, low levels or fluctuating levels of CO2, too much light, or a combination of all of these.

A tank that hasn’t been routinely cleaned can have a lot of waste and organics built up. These organics decompose and add nitrates into the water, which both live plants and algae use to grow. It's important to note that overfeeding fish or having an overstocked aquarium will lead to a larger amount of waste in the tank.

Most often, there is no CO2 or fluctuating CO2 levels in a tank with BBA. If there is a CO2 deficiency, BBA can take the carbon they require from hydrogen carbonate much easier than any aquatic plant in the tank. To explain further, black algae can separate the carbon from the hydrogen carbonate ion, which in turn creates hydroxide ions that elevates the pH. During this process, biogenic decalcification takes place, and calcium carbonate precipitates, which is then used by the algae to fortify their cell walls. Unfortunately, this causes the algae itself to become more difficult to remove, and more difficult for algae eaters to consume.

Consequently, low levels of CO2 mean the aquatic plants grow slower, so they aren’t able to take up as much of the nutrients. This leaves the black algae with the potential to use the excess nutrients to grow.  

 black beard algae in the fish tank

Is Black Beard Algae Harmful?

Black algae poses no threat at all to your aquatic creatures. However, the one thing it could harm is your aquarium plants. If BBA spreads enough to completely cover the leaves of a plant, the plant could essentially "suffocate" and die from the lack of lighting and nutrients.


5 Ways to Get Rid of Black Beard Algae

There are multiple methods of removing Black Beard Algae in the aquarium. Just note that these strategies are a temporary fix, as the algae are likely to keep popping back up until the underlying cause is addressed. We highly recommend reviewing your fertilizer dosing regimen, lighting schedule, maintenance routine, etc. Try to figure out where the imbalance in your tank is coming from.

Here are 10 tips to get rid of Black Beard Algae in the aquarium:


1. Liquid Carbon (Glutaraldehyde-based) Additives

Dosing liquid carbon products will help inhibit the growth of black algae, but it can also be used to eradicate it from plants or other objects contaminated by it. Flourish Excel by Seachem is a very popular liquid carbon product. There are two methods you can try with liquid carbon: spot treating or double-dosing in a separate container.

If you cannot remove the plants or items with BBA from the tank, then spot treating the BBA is the best way to treat your tank. To do this, simply use a pipette or dropper to directly drip the liquid carbon onto the black algae. Be careful not to overdose the aquarium with the additive. 

If you’re able to remove the contaminated plants and hardscape from the tank, then follow these steps:

  1. Add double the amount of the recommended dose based on the amount of water in the container and let them sit in there for 24 hours.
  2. After the 24 hours, change all of the water and let the plants sit in the clean water for 24 hours again.
  3. Repeat the whole process one more time before placing everything back into your aquarium.

This should kill off the BBA. If you’re using this method on plants, make sure to research that plant’s vulnerability to liquid carbon. There are some plants that are sensitive to these types of products and may be harmed, like Crypts and Vallisneria.

 black beard algae

2. Dose Hydrogen Peroxide (H2O2)

Hydrogen Peroxide (the 3% solution) is a common household item you can use to remove many forms of algae in the aquarium. Keep in mind that the recommended dosing is approximately 1.5 ml per gallon of water.

Similar to the liquid carbon, you can spot treat tough patches of Black Beard Algae by using a dropper or syringe to disperse it onto the affected areas. However, it's important to turn off your filter before and keep it off for 15 min - 1 hour after spot treating your tank.

  • This process should not harm your plants or fauna as long as you dose directly on the problem areas. However, it can harm the beneficial bacteria in your filter if you have your filter running during the process. Because of this, it's always a good idea to dose beneficial bacteria like SL-Aqua's Beneficial Bacteria for at least a few days after treatment.

For larger tanks or a for a more widespread BBA problem, you can also put it into a spray bottle before spraying it directly onto any BBA infested areas. Do this during a water change when the water level is low enough to expose the algae out of the water. Allow to sit for at least 5 minutes before flooding the tank again.

Another option is to place the affected plants and objects in a hydrogen peroxide bath for 3 minutes. You should notice the H2O2 causing the black algae to bubble up and turn red/pink. That is a sign that the hydrogen peroxide is killing the algae. Afterwards, you can attempt to gently remove the dead algae by lightly brushing with a toothbrush. If you'd rather not risk damaging your plants, simply place them back into the aquarium. Allow algae eaters like Amano Shrimp or Siamese Algae Eaters to remove the algae for you.


3. Add Algae-Eaters to Your Tank

There are a few aquatic specimens that are known to eat BBA. Arguably, the best fish for the job is the Siamese Algae Eater. They are known for eating black algae as well as other types of algae. The only concern you may have for these fish is that they get a bit large when they’re older, potentially up to 6 inches. Other black beard algae-eaters include Florida Flagfish, Amano Shrimp, and Nerite Snails.


4. Utilize SL-Aqua's BBA Remover

Although BBA is notorious for being one of the most difficult to clear, SL-Aqua Z3 BBA Remover aims to eradicate it! It contains a special formula that works to slow down reproduction and kill spores to remove BBA effectively over time. Pair dosing with a consistent maintenance routine and algae problems will subside. SL-Aqua's Z3 BBA Remover is safe for freshwater applications and will not harm aquarium plants or fish if dosage instructions are followed. 

 siamese algae eater crossocheilus

Siamese algae eater crossocheilus

5. Dose Green Water Lab's Algae Control

Aquascapers have seen great results when adding Algae Control to both algae prevention and treatment. It's made entirely from organic plant-based ingredients and is 100% safe for your plants and all fauna (including shrimp and snails.) After thorough testing by the Buce Plant team, it has been determined that Algae Control offers a simple and reliable solution for managing algae growth in freshwater aquariums. Black beard algae specifically can be a real nuisance, so it's recommended to spot-treat the algae with a dropper or syringe with Algae Control.

Additional Tips: How to Prevent Black Beard Algae

If you've already struggled with BBA and don't want to repeat the process, review these tips and tricks to prevent Black Beard Algae from appearing in your planted aquarium. Here are 6 tips to prevent black beard algae in the aquarium:


6. Never Introduce It Into Your Aquarium

Cliché, we know, but this is one of the best ways to prevent ANY type of algae is to never let it enter your aquarium in the first place. If you're ever setting up a brand new tank, always make sure all of the items going in are sterilized. If you're reusing old hardscape, substrate, etc., thoroughly clean everything first. Most importantly, always quarantine and/or perform a bleach dip on all of the plants going in your planted aquarium or use all tissue culture plants.


7. Add More Fast-Growing Plants

Plants are the number one competition against BBA for nutrients in the aquarium. It helps to have fast-growing plants like stem plants or floating plants because they use up more nutrients than the slow-growers like Buce or Anubias.

A major way to boost the growth rate of your aquarium plants is with steady CO2 injection. Plants grow much faster when CO2 is diffused into the water, and if all of the conditions are met, then the BBA won’t stand a chance against the plants.

 rotala narrow leaf sp red

8. Stabilize Your Lighting & CO2 Levels

Like many algae, BBA loves an abundance of light. A high-intensity light or a long duration of light can be feeding the Black Beard Algae in your aquarium, causing it to spread quicker. Try decreasing your aquarium's lighting schedule (we recommend no more than 6-8 hours a day), and/or decreasing light intensity by using a dimmer.

As mentioned previously, low CO2 or fluctuating CO2 levels can cause Black Beard Algae. Not only can increasing your already low levels of CO2 be important, but It's crucial to stabilize the CO2 levels in the tank so that it runs consistently for the same amount of time and at the same BPS. Make sure to use a drop checker to easily monitor CO2 levels in your aquarium.

For more information, click here for a guide on how to add CO2 to the aquarium (and keep it running properly).


9. Keep Up with Maintenance

We cannot stress this enough, but regular water changes are always important! From the moment you set up your tank, we recommend weekly water changes (or twice a week if you are experiencing high ammonia levels) to keep a happy balance in the tank. This will help lower the number of nitrates and other nutrients in the water by essentially replacing the “old” water that may be full of nitrates with clean water.

Most importantly, performing maintenance such as physically removing the BBA is important. You can take out/trim off infected leaves in order to prevent them from decomposing and releasing both ammonia and more algae spores into the water. In addition, regularly gravel vacuuming fish waste and uneaten food also prevent an overload of nitrogen from entering the system.

 aquarium water change
The Qanvee Siphon makes for easy water changes

10. Feed Your Fauna Less

Overfeeding is a common occurrence amongst hobbyists in the aquarium hobby. If you’re keeping up with maintenance and still see a lot of black algae blooming, it may be because you are feeding too heavily.

The amount of waste produced may be greater than the amount that you remove during water changes, so the BBA is still able to thrive. Try feeding less food to your fish and see if that helps with the issue. Keep in mind that your fish will be perfectly happy with only being fed no more than once a day.


11. Always Clean Your Tools After Maintenance

Thoroughly cleaning your aquascaping tools is especially important for those who have multiple tanks. If you're experiencing this stubborn algae in one aquarium, always clean your tools after performing any sort of maintenance before using the same tools in another tank. This is the easiest way for Black Beard Algae, or any algae at all, to spread and suddenly appear in a tank that wasn't experiencing any algae problems.


Tell us - Was this article helpful? Please leave a comment below!

If you have any questions regarding this article, please DM us on Instagram, Facebook, or email so we can assist you - @buceplant

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Yaron - December 4, 2023

Very informative and helpful.
I’d like to know your opinion regarding the use of UV light filters in fighting BBA

Bruno Pimenta - September 28, 2023

Thank you for the information and I’m going through the ‘treatment’ now let’s see how it goes.
One thing I noticed is that having Otocinclus, Garra Flavatra and even
Sewellia Lineolata don’t take care of this. Didn’t try the Crossocheilus Siamensis since they grow a lot for my aquarium size.

Chris - March 3, 2023

Great info. I am just suffering from black algae over plants and rocks. The tank is 7 months old. Was doing fine. Put the automatic plant light on the handset, which then made the light go on full for a staggering 11 hours. I thought because the remote set this it would be ok, but reading your article you state lighting only on for 6/8 hours. So I’m assuming that my algae is caused by the bright LONG time it was on. So reverting back to less light . And not full brightness. Fingers crossed

Jo Gurley - February 27, 2023

Very helpful info. This has been driving me crazy, though fish seem to enjoy hanging around in it. Algae eaters don’t make a dent in it, but like to hide in it. 😎👍

Steve Tuthill - February 27, 2023

Had some BBA spear in little tufts throughout the upper levels but it never really got “out of control” and in fact has now pretty much all but disappeared! So glad my little army of Florida Flagfish are a busy bunch! I enjoy a little algae in the tank so I do run my lights 12 hours and feed my fish as I feel they should be. Lots of live plants as well. …the Flag Fish and the Panda Garra’s love it!

Terry Summers - February 10, 2023

Thanks for the info.
I have to admit to feeding my fish twice daily and will now reduce it to once a day.
I also have my light on for 10 hours which I will reduce to 7 hours.
Will be visiting the shop for some treatment for the aquarium.
I have removed the infected leaves of the plants and also purchase some more faster growing plants hoping to compensate for the difficiency.
Lets see if this cures the BBA.

Joan Sitoski - January 9, 2023

Found this information very helpful. I have an outbreak in one of my tanks so willing to try most of these suggestions. Just leary about putting peroxide in my tank.

Amy Herrera - December 8, 2022

Well – I was struggling with BBA in a newish low tech 55 gallon in early summer. I looked up advice and carefully read what Tom Barr had to say, and cut water changes to once a month. (the tank is heavily planted with val and other plants, and I recently tested nitrates after 3 weeks with no PWC and they were at 0.) The BBA disappeared. I’ll have it grow on the output of the HOB filter, and sometimes old val leaves on the surface right in front of the output, but the rest of it left on its own.

Jose Porras - October 12, 2022

Good I will try the hydrogen peroxide

Alden smith - October 12, 2022

Needed this information so bad, thank you so much.

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