How to Remove Black Beard Algae in Aquariums

How to Remove Black Beard Algae in Aquarium

Black beard algae is a type of red algae that plagues freshwater and marine aquaria. It is commonly referred to as Brush algae because of its soft, fuzzy, hair-like filaments that grow attached to solid surfaces.

Black beard algae are one of the worst algae in the aquarium hobby because of how hardy, persistent, and stubborn it is. Sometimes it can be so difficult to eradicate that once BBA takes hold of a tank, it is easier to start a new one and I am completely serious.

In this article, I will enlighten you on all there is to know about this algae species, how you can get rid of Black beard algae for good, or prevent its appearance in the tank.

Black beard algae

What is Black Beard Algae?

Black beard algae or Brush algae (Audouinella sp.) is one of the most common types of algae encountered in the hobby. It belongs to the family of red algae and can be scientifically classified as follows:

Division: Rhodophyta
Class: Florideophyceae
Order: Acrochaetiales
Family: Acrochaetiaceae
Genus: Audouinella

It also grows very fast and when left unattended can grow up to 4 – 5 cm (2 inches) long.

BBA possess water-soluble pigments called phycobilins, which are localized into phycobilisomes, this gives them their distinctive color (ranging from dark green, browny grey to a deep black).

Black beard algae can be easily identified in the tank; in the initial stages, BBA appears as black or greyish spots on surfaces (decor, substrate, glass, leaves edges). As growth progresses, this algae will morph into thick patches of hair that are capable of enveloping plant leaves and covering hiding spots.

Note: Brush algae should not be mistaken for Staghorn algae; this particular algae has a wiry appearance and branching algae strands as opposed to single silky smooth strands of BBA.

Just like other red algae species, Black beard algae reproduce sexually (production of gametes for fertilization) as well as asexually. Asexual reproduction occurs through the production of spores and by vegetative means i.e. fragmentation and cell division.

Causes of Black Beard Algae

Black beard algae are mainly introduced to aquariums through contaminated plants, decors, and substrate obtained from pet supplies stores or other sources. The main causes of BBA growth in tanks include the following:

  • CO2: The lack of CO2 or fluctuations in CO2 levels can greatly aid the growth and spread of Black beard algae in your tank. When CO2 levels are unstable, plants can’t utilize the fertilizers and light available to perform photosynthesis.

If your aquarium suffers from inadequate water circulation, insufficient CO2 / fluctuations in CO2 levels, then you are creating an enabling environment for algae growth.

Solution: To combat this plague effectively, the provision of CO2 in the right quantity to your aquarium should be a norm; you can utilize a pressurized CO2 injector or simply add liquid carbon, Seachem Flourish Excel is a good example. This way you can easily top-up CO2 and there won’t be a spike in carbon levels in the tank by any measurable amount. Also, this has the potential of eliminating Black beard algae present in the tank.

  • Light: Aquarium plants enjoy light, so does Black beard algae. Turning the lights on for long hours is an open invitation for algae growth; the more light it has, the faster it grows and spreads in the tank.

Solution: Reducing the photoperiod will slow down the rate of growth/spread of BBA in your tank, this can be enforced using an automatic timer that will turn the LED lights on and off each day.

  • Nutrients: Excess of nutrients can also lead to Black beard algae.

Solution: Do not overfeed.

Is Black Beard Algae Harmful to Fish or Shrimp?

Black beard algae will not harm fish, shrimp, and other animal species in your tank directly because it is not toxic or poisonous to them. However, you will need to remove algae from your tank without delay as they are likely to wreak havoc and make life uncomfortable for flora and fauna.

Here are some reasons why you need to get rid of it:

  • BBA can cling to every hard surface in the tank: driftwood, glass, filter pipes, rocks, even the shells of snails; thereby turning the tank into a black mess of hair-like growth which can be unsightly when left unattended.
  • This fuzzy algae has the potential to block access to hiding places that bottom dwellers, shrimplets, and shy fish like to roam around.
  • Excessive growth of Black beard algae will ultimately cause an imbalance in nutrients and will lead to an unsafe environment for animal species. It can also increase the stress levels of fish by reducing the space they need for their activities.
  • If you keep Fish species that love to eat plants will find plants covered by Black beard algae unattractive.

Some fish species will enjoy swimming and hiding in the fuzzy, long flowing hairs of Black beard algae. Although this is not enough reason to allow them to grow in your tank, you should eliminate it.

Is Black Beard Algae Harmful to Plants?

Yes, Black beard algae will harm your plants. BBA is not poisonous per say; you will notice them growing on the edges of your plants. Slowly but surely, it will begin to spread and smother the plants by covering the whole leaf surface including the stems.

When this occurs, light is less likely to reach the plants, and this is vital for most aquarium plants to survive. In the absence of light, plants cannot carry out photosynthesis and they will die in the long run.

Therefore, the presence of Black beard algae should not be taken lightly, as an uncontrolled spread is lethal to the health of plants in the aquarium: BBA competes with plants for available nutrients and also blocks off light from getting to them.

Methods of Eliminating Black Beard Algae

Black beard algae infestation is not something any hobbyist should take lightly, its spread can be devastating if left unattended. At this point, the big question comes up; how can one get rid of Black beard algae in the aquarium?

Although there are many methods for removing BBA from tanks not all of them can work for all tanks. In addition, the efficiency of the method can vary depending on the level of infestation and tank set up.

1. Biological – Introducing BBA Eaters

This method of combating Black beard algae is through the introduction of algae-eating species. Some species of fish and crustaceans will help in controlling the presence of BBA in your tank. However, you should bear in mind that this method may not be as effective as others mentioned in this article.

According to multiple reports, the following species can help to control BBA:

Unfortunately, many aquarists also have had a varying degree of success in controlling Black beard algae with algae-eating animals. In some cases, there was no positive result at all.

Potential problems:

  • Keep in mind that many of the aforementioned species are more likely to feed on algae in the absence of any other food source in the tank. In other words, they must be hungry.
  • Hungry animals may also try to find another source of food in the tank instead of eating BBA. For example, they can even turn against plants.
  • Some setups can be too small for the algae-eating fish.
  • Compatibility with other fish, shrimp, snails, etc. can also be a problem.
  • These species can eat Black beard algae when it is new and fresh. Once it gets bigger and becomes coarse, they will pretty much ignore it.

2. Boost CO2 level in the Aquarium vs BBA

This method is a more effective way of getting rid of Black beard algae and involves an increase in Carbon dioxide levels (CO2) in the tank. This process will not eliminate algae on the spot, but will gradually inhibit its growth until it eventually ceases to exist.

Increasing the CO2 level will also promote the growth of plants, which in turn reduces the nutrients available in the tank for algae growth. You can boost CO2 levels in two main ways:

  • CO2 injectors in the form of pressurized CO2 cylinders.
  • Liquid Carbon e.g. Seachem Flourish Excel, Easy Carbo (read below).

Potential problems:

  • If you keep shrimp or fish in the tank and plan to use the CO2 method, I would highly recommend learning more about the subject. Adding too much CO2 will cause low O2 concentrations (that can cause suffocation) and the pH to drop, which can also shock the animals in the tank.

For more information, read my article ”CO2 in a Shrimp Tank”.

3. Flourish Excel, Easy Carbo, etc. vs BBA

This alternative to gaseous CO2 injection works in a slightly different manner compared to CO2 gas.

It contains a chemical called Glutaraldehyde which acts as a disinfectant when applied to the tank water, it will cause the Black beard algae to slowly wither and die. Alternatively, you can try spot dosing. This involves using a pipette or syringe to apply Seachem Excel directly to the algae.


You have to understand the danger and take responsibility!
If you do it, you do it at your own risk!

  1. The is not just to dose it but to overdose
  2. Day 1 – use a standard dose of Flourish Excel.
  3. Day 2,3 and 4 – use a double or triple

Dose in the evenings, toward lights out, it will increase the efficiency.
In a day or two, you should notice that Black beard algae turn reddish or purple. It means that it is dying. After some time, it becomes white and begins falling off.

Tip: Clean your equipment and trim the plants which were infected by BBA. It is also recommended to keep using Flourish Excel (normal dose) for some time to prevent BBA from coming back.

Note: If you have BBA only in several places, it can be better to use a syringe and treat these places individually instead of treating the whole tank. The principle is the same. The only difference is that you need to turn off the filter during treatment for 5 – 10 minutes.

Potential problems:

  • Overdosing can be lethal to your fish and shrimp.
  • Some plant species may melt away and die. For example, be careful with sensitive plant species like Val’s.

If you see that fish are gasping at the surface, it is the sign of too much CO2 in the tank. Decrease the dose and do a water change.

Many types of Val’s are sensitive to Flourish Excel, and will melt away and die. I know of no other plant that this happens too.

4. Hydrogen Peroxide (H2O2) Bath vs BBA

You can always remove BBA from aquarium by using hydrogen peroxide (3%), this can be obtained from local pet stores.
To get rid of algae from plants, you have to remove any affected ornament or aquarium plants and soak them in a bath of diluted 3% Hydrogen peroxide for 3-5 minutes.

At the expiration of this interval, remove the affected ornament or plant from the bath and rinse them thoroughly using freshwater. Afterward, you can allow it to air-dry before putting them back into the tank.

Potential problems:

  • Some plants can be very sensitive to Hydrogen peroxide. For example, plants like Monte Carlo, Dwarf baby tears, Vals, Mosses, Monoselum tenarum, Susswasertung, Riccia, Hemanthius glomeratus, etc.

5. Hydrogen Peroxide Injections vs BBA

If it is not possible to take out plants, decorations, etc. from the tank, we can spray Hydrogen Peroxide to the infected area using a syringe or treat the whole tank.


You have to understand the danger and take responsibility!
If you do it, you do it at your own risk!

Luckily, we have a relatively safe level of H2O2 that I mentioned in my articleHydra in a Shrimp Tank. Treatment”.

  1. Turn off your filter
  2. Use 3% Hydrogen peroxide at 1.5ml per gallon or per 4.5 liters.
  3. Evenly spread H2O2 across the surface of the aquarium.
  4. Gently stir the water to spread it.
  5. Wait for 60 minutes
  6. Turn your filters back on.
  7. The same week do a water change and add your favorite bacterial supplement back to the tank.

Ideally, it would be better to remove all animals, wait for a few days, do a massive water change before putting them back. 

Potential problems:

  • Hydrogen peroxide can kill the beneficial bacteria in the nitrogen cycle because it does not have the necessary enzymes to metabolize the H2O2.

Note: If you have BBA only in several places, it can be better to use H2O2 via syringe, slowly injecting it into a mass of algae, instead of treating the whole tank. The principle is the same. The only difference is that you need to turn off the filter during treatment for 5 – 10 minutes.

6. Seachem Flourish Excel + H2O2 vs BBA

Seachem Flourish Excel and H2O2 vs Spirogyra Hair AlgaeBasically, this is a combination of both methods – a 50/50 mixture of 3% Hydrogen peroxide and Seachem Flourish Excel.
Hydrogen peroxide link to check the price on Amazon.
Seachem Excel  – link to check the price on Amazon.

Potential problems:

  • Hydrogen peroxide + Flourish Excel can be too much for your livestock and plants to handle. This is very dangerous but also effective.

You can check out video how it works, just keep in mind that draining the tank down until the plants are exposed is super risky! The concentration of this treatment will be simply extreme. In addition, huge water changes can cause serious molting problems for the shrimp.

Therefore, I do NOT recommend to drain the tank if you have shrimp. They will die.

Note: If you have BBA only in several places, it can be better to use a syringe and slowly injecting it into a mass of algae, instead of draining and treating the whole tank. The principle is the same. The only difference is that you need to turn off the filter during treatment for 5 – 10 minutes.

7. Tetra Algizit vs BBA

Tetra Algizit is highly effective against different types of algae including stubborn Black beard algae. According to the manufacturer, it is not harmful to fish, plants, and micro-organisms when used in accordance with instructions.

Recommended dosage:

  1. Add 1 tablet per 20 liters (5 gallons) of aquarium water.
  2. Repeat dosage after 4 weeks if needed.

According to Italian, Spanish and Russian forums, chemicals such as JBL’s Algol are the usual solution to getting rid of BBA.

8. Darkening the Tank

This is one of the easiest ways to get rid of Black beard algae. Without light, BBA will die off.

Potential problems:

  • It can harm plants that require a lot of light but they should survive.

How to do a Blackout:

  1. If you have fish, feed them a regular amount of food. Do not overfeed. If it is a shrimp tank, you may even skip this step.
  2. Turn off the CO2.
  3. Do not add fertilizers during the blackout.
  4. Increase the oxygen supply. Install a new air-pump if needed.
  5. Cover the tank with a thick blanket. It must be completely dark in the tank.
  6. Leave the tank this way for at least 3 days. Some aquarists recommend 5 days.
  7. Open up half of the tank and leave like this for 30 minutes. Let your fish adapt.
  8. Remove the blanket completely and wait another 30 minutes before switching the aquarium light on.
  9. Clean equipment as the dead BBA can clog it easily.
  10. Do a water change. If it is a fish tank, it can be 50% water change. If it is a shrimp tank – 10% water change.
  11. Change your light timer to 4 – 5 hours for the next week.

9. Regulating the Amount of Phosphate in the aquarium

Phosphate naturally increases as wastes are broken down in the aquarium. If the tank is not properly maintained, the phosphate level will continually rise and contribute to algae growth.

Phosphate sources include: dead fish, uneaten food, fish waste, pH & kH buffers, decayed plant matter.

Phosphate level can be kept low through the following ways:

  • Tank maintenance: Ensure that the tank is free from debris and algae. You can do this by scraping the glass, also remove the rocks and decors, and scrub them as well. The bottom of the tanks should be vacuumed frequently to get rid of plant decay, uneaten food, and fish waste. Performing regular water changes will also help to keep the phosphate at a desirable level.
  • Feeding: Avoid overfeeding your fish or shrimp. They should be fed sparingly and any uneaten food removed promptly.
  • Filtration: The use of phosphate absorbing filter media.

10. Heat method

This method is recommended if you desire a chemical-free approach. Here, you have to remove any algae infested ornament from the tank and boil them. Bear in mind that this method doesn’t work with live plants and plastic decor.

Take out all items covered in algae and add them to a container. Next, you can either pour boiling water over the affected items and allow them to cool off, or boil everything in the container for about a few minutes to kill all Black beard algae.

11. Manual Removal

To put it in a nutshell, this method is completely ineffective without any other mentioned above. However, it is a great way to improve the results.

  • Trim the affected plants
  • Try to physically remove as much algae as possible.

Use algae scrapers or a toothbrush, for that.

How to Prevent Black Beard Algae

It is of great importance to carry out preventive measures in order to avert the growth and spread of Black beard algae. Here are some tips that can help prevent BBA outbreak in your tank:

  • Purchase plants from reputable stores. Most fish stores have established methods for preventing the transfer of parasites to customers’ aquaria. Also, never take plants and animals from the wild, that’s the quickest way to introduce hitchhikers to your aquarium.
  • Quarantine / disinfect new plants with bleach/potassium permanganate solution, a hydrogen peroxide bath can also be utilized for this purpose (Read more about it here). This will help prevent the introduction of algae as well as a host of other parasites and diseases.
  • Quarantine all new animals (fish, shrimp, snails, crabs, crayfish, etc.) and do NOT allow the water they came in to mix with your tank water.
  • Always monitor light levels and don’t allow the lights to stay on for long hours. High light intensity for long periods will boost algae growth.
  • Perform routine water changes. It will go a long way in preventing algae growth.
  • Do a vacuum cleaning on the substrate to remove dirt as much as possible.
  • Add live plants in order to compete with algae for available nutrients. In addition, ensure that the aquarium has enough carbon dioxide which plants will use up for photosynthesis.
  • Use a filter that is powerful enough for your aquarium. The essence of having a good filter is that it guarantees a sufficient flow of water in the tank and it will help regulate phosphate levels.
  • Do not overfeed your fish.

In Conclusion

Black beard algae are one of the hardest algae to kill off. It usually appears if there is an imbalance of lighting, CO2, or nutrients.

Do not let it take hold and take over your tank.

Remember that you cannot fight algae by fighting the algae itself. You have to find what caused the algae and you need to work on eliminating that cause.

Related article:

How to Remove Black Beard Algae in Aquariums

6 thoughts on “How to Remove Black Beard Algae in Aquariums

  1. I had this one and google searches suggested it was CO2 problem, O2 deficiency, and Organics. I strongly believe this algae doesn’t like high oxygen levels but I couldn’t prove that. I did Have a deep layer of gravel substrate with some organic in it. But a deep vacuum wasn’t able to remove it all and if anything made the problem worse. Since I wanted to switch to black diamond blasting sand I elected to change the substrate. I removed the substrate but left the plants in the water and didn’t touch the filter. After removing the gravel and several water changes to remove and the remaining organic Much off BBA on the glass died. The rest on some of my plants and the outside of the filters completely stopped growing and maybe died. But it didn’t fall off or melt away. put the black sand in and arranged the plants and then reintroduced nerite snails and they then cleared off all of the algae on the glass, and then slowly removed much off BBA on the outside of the filter. The recovering pond snail population also helped clear what was left on the plants.

    There is less void space in the sand so I hope that will prevent organics from building up in the substrate. I never sterilized the filter but there is some BBA inside the filter. But it is currently staying inside the filter. and not causing any issues.

    1. Hi Steven F,
      Thank you for sharing your experience!
      Best regards,

  2. I have a 125l tank which had 3 goldfish, 4 nerite snails and 6 amano shrimp living in it. Originally I had live plants but between the goldfish eating them and bba, most of them have died. I have tried several methods as described above to get rid of the bba but nothing has worked permanently.
    I have now moved the fish into a pond outside and have stripped the tank completely. I have boiled all the rocks and gravel in a pan on the stove and I have removed everything except the Fluval U4 internal filter which is now running without any cartridges in it. I will put all new cartridges in when I set up the tank again.
    Yesterday I refilled the tank to the top and put 6 Tetra Algizit tablets in.
    My questions are,
    How long should I leave this set up running to be sure to have killed all the bba in the tank and filter?
    Should I empty and refill the tank with fresh water a couple of times before setting it up again?
    I am planning to set the tank up as a cold water community tank with live plants shrimp and nerite snails again, would it be safe to put the original shrimp and snails back in the tank. They are currently living in a small tank which also has bba, or is there a safe way to treat them before reintroducing them into the clean tank?
    Any advice would be gratefully received!
    Kind regards,
    Vicky Graham

    1. Hi Vicky Graham,
      Just keep it running. There is no need to do anything extra.
      As for the shrimp and snails – I’d wait for at least a weak before adding them to the tank.
      Maybe I am too overcautious but in my experience, I have had some really bad results with so-called invert safe products (not with this product though).
      Again, maybe it was just bad luck but nowadays I prefer to play safe.
      Best regards,

  3. Been fighting BBA for years now. Finally decided to try and GET RID OF IT for GOOD ! Ran across FLOURISH about 6 months ago and used it as recommended. IT WORKED pretty well. I had BBA that was 2″ long and worse ! Flourish knocked it for the most part! But then after a month or so, it started coming back !!! Started to use the Flourish again and is knocking it down, but not out ! Thinking of following your example with the Hydrogen Peroxide / Flourish 50/50 mix and see what happens.

    Several years ago I had taken the whole tank completely down because of BBA ! {55 gallon tank} I have two power heads on it and a bottom filter, one at each end. Scrubbed the whole inside with bleach. Soaked the gravel with the bleach too ! Soaked everything I could get with bleach. Then allowed it to dry outside for a few days before washing it again with clean water.

    Put it all back together again and it was beautiful !……. for awhile. Then about a year later, BBA CAME BACK ! HOW ?! No new plants {I was using all plastic then. Had soaked and cleaned all the rocks, etc from inside. Thought I had beaten it, but….. Then happened to run across your video by accident. {I would like to think it wasn’t by accident}.

    A couple of weeks ago I introduced 10+ Sunkist orange shrimp {1/2″ – 3/4″} into the tank. They scampered all over the tank looking over their new surroundings. {All Live plants now} The next day they were ALL GONE ! Quite a disappearing trick ! {Guess they’re good at this ?!} While doing some routine cleaning yesterday I found ONE lone shrimp {3/4″}, but today he too has disappeared – again ! The only fish consist of about a dozen guppies, two Zebra Danios {M & F}, three Black Neon Tetras, and a couple of Cory’s. None of which would or can eat those shrimp.

    Any suggestions ?

    1. Hi Al Schatz,
      Thank you for the feedback!
      Fighting algae such as BBA or Staghorn can be sometimes tricky.
      As for the shrimp, well, actually, Zebras, Neon tetras, and guppies are not recommended to keep with shrimp.
      They seem small and inoffensive but they are not for the shrimp.
      They can pick on shrimp continuously and dismantle them eventually!
      In addition, any recently molted shrimp is a free meal.
      Check out my article – Сherry Shrimp in a Community Tank. Tips to Make it Successful.

      Best regards,

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