Last update: December 12, 2023

Identify and Beat Black Beard Algae (In just a few days!)

Let’s face it:

Beards look better on your face than they do in your aquarium!

In an aquarium, it just looks like a fuzzy mess.

I’m talking about black beard algae. The bearded monster that can quickly take over your tank.

Today, I am going to show you how to identify it, get rid of it, and stop it from coming back!

What is black beard algae and how to identify it?

I love it when things are named after what they look like, and black beard algae is certainly that – a black algae that looks like a scruffy beard. It is also referred to by the name black brush algae or by the initials BBA.

While black beard algae is considered to be a saltwater algae, there are strains that are common to freshwater tanks. In fact, in all my years of fishkeeping, I have probably seen more freshwater tanks become plagued by this bearded menace than saltwater ones.

It may surprise you to learn that despite its name and look, black beard algae is actually a member of the red algae family. This shouldn’t surprise any of you who have killed black beard algae before – it turns a red color as it dies.

However, when it is healthy, black beard algae’s color ranges from a dark green, browny gray to a deep black. While its color may vary, one thing remains constant – its look.</p

Just like a beard, this algae starts out as light stubble – small spots of fuzz that cling to the surface of anything in your aquarium.

Small black beard algae spots growing on stem of plant

As time passes, the black beard algae looks more like three-day growth…

Black beard algae growing around the edges of a leaf in aquarium

But if left unattended, it soon grows into a glorious, thick and brushy, hair jungle.

Fully grown, brushy brown black beard algae in aquarium

Seriously, it looks like hair straight out of a shampoo commercial!

Like most algae, black beard algae draws its nutrients from the water. This allows it to grow on virtually any surface in your aquarium including…


Driftwood in aquarium covered in black beard algae

Filter pipes and airline tubing…

Black beard algae growing on plastic filter pipe in aquarium

On the surface of your substrate…

Black beard algae growing in quartz substrate in aquarium

Even on the shell of your snail!

Black beard algae growing on snail shell

My point is that black beard algae can grow anywhere. Decorations, rocks, even on the glass of your fish tank!

Black beard algae is easiest to spot when it grows on plants. It typically grows on the edges of the leaves before expanding and covering them completely.

Don’t be confused with…

Black beard algae is often confused with staghorn algae. And, I can see why – fully grown staghorn algae looks much more like a wiry beard than black beard algae does.

So, how do you tell the difference?

Let’s compare the two during their early stages of growth…

Black beard algae vs staghorn algae side-by-side comparison

In the blue circle, you have black beard algae, resembling the tightly packed clusters of bristles you find on a makeup brush. Staghorn algae, circled in red, looks more like the antlers of a male deer – hence the name.

When fully grown, the two also look quite different, but unless you compare them side by side, it’s easy to see where the confusion comes from.

Fully grown black beard algae vs fully grown staghorn algae side-by-side comparison

Fully grown black beard algae, on the left, is dense and bushy while staghorn algae, on the right, is sparse and wiry.

For more information and pictures (and how to beat it), check out our in-depth staghorn algae guide.

Is black beard algae harmful to fish?

Fish hiding inside black beard algae without harm

Nope, black algae is not dangerous to your fish.

In fact, if you let your black hair algae grow, many fish happily swim and hide in the long flowing hairs.

Plants on the other hand…

Is black beard algae harmful to plants?

Yes… But not directly.

Let’s say that you notice black beard algae beginning to grow on the edges of one of your plants. No harm done.

The problem is… As the algae begins to spread, it blocks out more and more light.

And if you know about photosynthesis, you are fully aware that light is vital for most aquarium plants to survive. Without it, they die.

So yes, an uncontrolled spread of black algae can be particularly dangerous to plants in your aquarium.

You May Also Read – How to deal with brown algae?

Do you need to remove black beard algae?

For most beginners (and even some experts!), black beard algae appears when something isn’t quite right in your tank – creating the perfect environment for it to grow.

If the cause isn’t fixed, black beard algae will continue spreading until it takes over your entire tank.

In this case, the answer is obvious:

You want this bearded menace gone, and you want it gone now!

And, that’s just fine. In fact, I would argue that the majority of hobbyists view black beard algae as an ugly menace that needs to be eliminated.

However, there are some instances where black beard algae can be a welcome addition to your aquarium. Just keep in mind that those who encourage black beard algae are experienced and know what they are doing.

It may surprise you to learn that some fish keepers voluntarily add black beard algae to their aquarium. Yep, what many people consider a pest can also become a beautiful plant when properly maintained.

Black beard algae completely covering an aquarium mask decoration

This fish keeper allowed black beard algae to completely cover a decoration in her aquarium, creating a spooky mask that moves in the water.

Another fish keeper let black beard algae grow all over a sunken log in his aquarium…

Black beard algae growing over log with kuhli loach fish hiding inside
Khuli loach (Pangio kuhlii)

The result is a lovely centerpiece that his fish love to hide in.

As you see, if you know what you are doing, black beard algae isn’t always bad news!

What is the cause of black beard algae?

One day it isn’t there, then the next day it is. It feels like black beard algae magically appears on its own, right?

Well, it may surprise you to learn that black beard algae needs a little help from you.

Like most plants, algae requires certain conditions to thrive. If these conditions are met, black beard algae spreads across your tank like wildfire. Well, underwater wildfire anyway.

There are two common causes of black beard algae…

1. CO2 fluctuations

It is generally accepted that CO2 fluctuations are the number one cause of black beard algae.

If your CO2 levels are too low, your CO2 is fluctuating or you have poor water circulation, you are creating an environment that is perfect for black beard algae to grow.

If you have black beard algae, getting your CO2 levels in order should be your first priority. It could be your CO2 canister is running low, there is a blockage or you are not injecting the correct amount.

Don’t run a CO2-injected tank? Your unstable CO2 levels could be a result of water changes – a large water change can significantly fluctuate the CO2 levels in your tank.

If this is the case, and you have a planted tank, I highly recommend dosing with Seachem Flourish Excel. It is a simple additive that provides your plants with a source of carbon, and, as I will discuss later, can be used to effectively kill black beard algae.

2. Too much light

Like many algae, black beard algae loves light. The more light it has, the faster it spreads. This is a particular problem for those of you with planted tanks – that LED grow light isn’t just helping your plants to grow but algae too.

If you leave your aquarium light on for long periods of time (or never turn it off), then you are basically encouraging algae to enter your aquarium.

Reducing the amount of time that light shines on your aquarium can slow or even stop black beard algae from appearing altogether.

I recommend using a reliable aquarium timer to automatically turn your LED lights on and off each day. It’s easier than manually doing it– something you will certainly forget to do.

Check out our detailed guide on aquarium timers for more information, including which timer is best for your aquarium.

Do you also have trouble with blue-green algae? Check out how to deal with it.

How do you remove black beard algae?

Important: To treat black beard algae, never scrub or pick at it. Your effort of removing black beard algae by scrubbing it can cause small pieces to float and settle on other plants or decorations in your aquarium, causing it to spread faster than before.

As mentioned earlier, Black beard algae don’t necessarily release any harmful toxins. But, a thick layer of Black algae can kill any plant in your tank while also creating an imbalance in your aquarium ecosystem.

Lastly, it isn’t a very visually stimulating sight to look at. Many aquarists dislike Black algae because of its stubborn nature, which is extremely hard to get rid of.

Your black algae problem typically won’t go away on its own. Not without fixing the cause first – and even then, established algae in your tank will probably require a little effort on your part to banish it for good.

However, we would like to introduce a few methods to help eliminate Black beard algae. Use the tricks below to treat black beard algae in your aquarium.

So, you want to make your black algae problem go away for good?

Method 1. Cut, cut, cut

This solution will only work if black beard algae has just begun to appear in small numbers on your plants. If black beard algae has already taken over your tank, skip to the next step.

If you see the dreaded black fuzz growing on the edge of your plant leaves, simply cut the entire leaf off at the stem and remove it from your aquarium.

However, a haircut alone will not save your tank – there are very likely other small pieces of black beard algae lurking in your tank, just waiting to make an appearance.

So, the next step is to treat the water with…

Method 2: Treat Aquarium With Hydrogen Peroxide

peroxide treatment

Hydrogen Peroxide is your best bet to get rid of a heavy concentration of Black beard algae in your tank. Aquarium hobbyists can purchase this over-the-counter chemical at drugstores. In addition, we highly recommend aquarium owners keep a bottle handy for solving many tank-related issues.

If your decoration, substrates, and plants have a layer of Black beard algae, consider removing them from the tank and soaking them in a Hydrogen Peroxide solution.

Ensure that you prepare the bath with 3 percent Hydrogen Peroxide and remove the decorations and plants in three minutes. The next step is to rinse all the decorations with fresh water to remove even the slightest amount of Hydrogen Peroxide.

However, consider treating your entire tank with the chemical if these affected decoration pieces and plants aren’t removable. We recommend using 10ml of three percent Hydrogen Peroxide per fifteen gallons of water.

You will soon start noticing the algae’s color fading, and in a month, you will get rid of the entire algae problem. You can also repeat this process twice or thrice or increase the concentration as Black algae are pretty stubborn.

If the plants are sensitive, you can lower the ratio under 1:3 to keep them alive and thriving. Since Hydrogen Peroxide leaves zero residues, you do not have to worry about scrubbing the rocks and plants.

Note: You will notice your plants changing color when they come in contact with Hydrogen Peroxide, but the plants’ color should return after some time. A minimal quantity of the chemical won’t necessarily cause any harm to the fish, but one can always move the fish to a new tank during the process.

Potential Issues To Consider

  • Plants like Monte Carlo, Monosolenium Tenerum, Riccia, Hemianthus Glomeratus, Subwassertang, Dwarf baby tears, etc., are susceptible to damage from chemicals like Hydrogen Peroxide.
  • Hydrogen Peroxide may kill most of the beneficial bacteria in the nitrogen cycle.

Method 3: Boosting Carbon Dioxide (CO2) Levels In Aquarium

Boosting the Carbon Dioxide levels in your aquarium can be an effective way to get rid of stubborn Black beard algae.

Hobbyists must note that the process won’t eliminate algae spontaneously, but it will highly inhibit its growth, thus eventually ceasing it to exist.

This method is also excellent for aquariums that are running low on CO2. A great sign is to see the texture of the algae. If it is stiffer than normal algae, your aquarium has lower Carbon Dioxide levels.

To boost the CO2 levels in your tank, you can either opt for Carbon Dioxide injections available in the form of pressurized CO2 cylinders or use liquid carbon like Easy Carbo, Seachem Flourish Excel, etc. We recommend aiming for approximately 20-25 ppm if the oxygen levels of your aquarium are already in a healthy range.

Seachem Flourish Excel to remove black beard algae

If removing black beard algae is not an option or too difficult now, this stuff is simply amazing! Not only does black beard algae hate it, but it will improve the growth of the other plants in your aquarium. This will be especially noticeable if you don’t already inject CO2.

Using it is simple. Just follow the instructions. In my last tank, it took just a few days before I began to notice the black beard algae wither and die.

Ensure that your water flow is adequate to deliver the Excel to every corner of your tank.

If you don’t notice a change, double dosing may be required. Alternatively, you can try spot dosing. This involves using a pipette or syringe to apply Seachem Excel directly to the algae.

Below is a quick video on just how effective spot treatment with Excel is!

If you take this route, ask an expert about the amount of Excel you should use for each dose – the amount will vary according to the size of your tank and the number of fish that is stocked.

Black beard algae often turns a red/pink as it starts to die before finally turning a clear, white color as it dies.

Black beard algae turns pink as it begins to die
Photo Credit: Ryan R

This dramatic color change is actually very helpful because it’s obvious which areas you need to treat next!

Potential Issues To Consider

  • If you have shrimp or sensitive fish in your tank, be careful about this method. Pumping too much Carbon Dioxide can result in lower Oxygen levels and a considerable pH drop, and these changes can indeed shock the aquatic life in your tank.

Method 4: Regulating Phosphate In Your Aquarium

Everyone knows that phosphate is the ultimate byproduct of almost all the edible and organic materials in your aquarium tank.

If you weren’t aware of this, remember that dead plants, fish waste, fish food, and random organic products produce phosphates that directly encourage the Black beard algae to proliferate.

Regulating and reducing the phosphate level will starve the Black algae, making it weaker and finally eliminating it. Apart from organic materials, your tank’s phosphate levels can rise with the constant use of hydrogen ion buffer solution, carbon filter media, kH buffer solutions, aquarium salts, and tap water.

Yes, you heard it right; tap water can also contain high levels of PO4 that can help the growth of Black algae. If you are dealing with Black algae almost constantly, consider testing your water’s phosphate levels. Black algae can successfully thrive in phosphate levels of 1ppm and above.

If your test showcases digits resembling one or above, we recommend following one of the following suggestions:

  • Choose another water source to reduce your chances of encountering Black beard algae. Generally, purified water or distilled water with reverse osmosis will keep a check on your algae growth. However, ensure that you are remineralizing your water before using it for the water tank. Find a phosphate-free remineralizing solution like Seachem Equilibrium to re-introduce all the minerals depleted in the purification process.
  • If the first option is too tedious, we suggest adding phosphate-absorbing media to your tank’s filter. A canister filter will work the best for such cases.

Potential Issues To Consider

  • Avoid overfeeding your fish to keep the phosphate levels in check. Please take notice of any uneaten food and remove it before it releases phosphate.

Method 5: Introduce Black Algae-Eating Fish In Your Fish Tank

This method is a purely natural way of controlling the robust growth of Black beard algae in your aquarium tanks.

The principle behind this method is simple- introducing algae-eating fishes in your water tank. You will be surprised to know the varieties of fishes that consider Black algae their primary food source.

Well, there is!

The true Siamese algae eater.

Siamese algae eater chewing on algae
Siamese algae eater

Siamese Algae Eaters, also known as SAE fishes, are famous for feasting Black algae. They can devour even the most robust growth of Black beard algae all by themselves.

However, do a little research and purchase the correct species of fish. We recommend combining these fishes with CO2 injection or Hydrogen Peroxide soak for better results.

Both the methods will make the algae weak, soft, and tender for the fish to eat. Apart from Siamese Algae Eaters, the following species can feast on Black beard algae with the same enthusiasm:

  • Black Molly
  • Bristlenose pleco
  • Rubber lipped pleco
  • Twig catfish
  • Common Goldfish
  • Rosy Barb
  • Cherry Barb
  • Pygmy suckermouth
  • Chinese Algae Eater

You see, there is no guarantee that this fish will eat the black beard algae in your tank. Like humans, fish have preferences to the type of food they eat, even among the same species.

And even if your Siamese algae eater does have a taste for black beard algae, it might not be able to nibble the algae fast enough to completely remove it from your aquarium.

This is also a common problem with shrimp as with Siamese algae eater. While they do eat black beard algae, they cannot eat it fast enough to make a noticeable difference.

Check out the video below. Despite the shrimp constantly chomping at black beard algae, they can’t keep it in check.

If you want to stick to a proven method that works, and you don’t want an extra mouth to feed!, I recommend using the Seachem Flourish Excel dosing method.

Potential Issues To Consider

  • Many fish species mentioned above prefer eating Black algae in the absence of other food sources. So they must be hungry with no food near their habitat to initiate eating Black beard algae.
  • Some aquariums can be small and contested for algae-eating fish. Ensure your tank isn’t overcrowded.
  • These hungry fishes may start eating your plants inside the tank if you stop feeding them. Pay close attention to the compatibility as you do not wish to pair a few dominant fishes with a single submissive fish.

Method 6: Heat Treatment

heater inside aquarium

Heat treatment is a safe and harmless option if you do not want to play with potentially harmful chemicals. Algae prefer a warm environment, but too much warmth can welt the Black algae.

Before initiating the process, you need to transfer your fish to different tanks to keep them safe. Consider placing your live plants in that other tank too. Insert a heater in your Black algae-riddled tank around 110°F to 120°F for an hour.

If your live plants have a layer of Black algae, place them in a Hydrogen Peroxide mixture in the meantime. The heat in the tank will slowly and effectively burn the Black algae causing it to die without using any harsh chemicals in the process.

Potential Issues To Consider

  • Remember that this method isn’t suitable for live plants or plastic decoration. Live plants will surely burn while the plastic decor will melt within minutes.
  • If you opt to boil your Black algae-infested pebbles and rocks, ensure to use a pot with a tight-fitting lid. Most porous rocks may pose a threat of explosion when exposed to intense heat.

Method 7: Cutting The Photosynthesis Of The Black Algae

We do not recommend this approach if your tank has multiple plants. However, if your tank has no plants or a single removable live plant, go ahead with this method.

This cure won’t eliminate your Black algae infestation instantly, but you can surely get rid of the growth over time. Consider switching off the artificial lights of your tank for four days.

If you have your fish tank near sunlight, take it inside or wrap it with a black cloth. After the first four days, reduce the daily light dose by half. You will soon notice a steady decline in the growth of Black beard algae.

Potential Issues To Consider

  • Plants that require a lot of sunlight won’t thrive in such conditions.


All aquarium enthusiasts can agree that these Black beard algae are the most stubborn algae variety.

While it may not be harmful to fish, unwanted black beard algae can soon cover every corner of your tank – and to many, it looks darn ugly.

However, by maintaining proper tank parameters, and careful attempts on removing black beard algae, you should be able to prevent black beard algae from appearing in the first place.

How did you get rid of black beard algae in your aquarium? Let me know in the comments below!

Ian Sterling

Ian Sterling, founder of, began his aquarium journey over 30 years ago, driven by a deep fascination for fish and their diverse personalities. His website,, is dedicated to making fishkeeping accessible and enjoyable, offering beginner-friendly guidance, expert insights, and a community for aquarists to connect and share experiences.

Comments (88)

I used flourish excel on a shrimp tank and I had 90 percent shrimp death so I discontinued. Then I read that liquid carbon can be harmful to some invertebrates like crystal red shrimp. I can’t figure out any other alternative methods to eliminate BBA. So frustrating.

Great article, and all too familiar with our situation.

This stuff is a nightmare! We are battling it as I write this. We have used Excel, H2O2, and mechanical removal methods and are slowly winning the battle. We are documenting the process in hopes that it will help others to not make the same mistakes we did. We even went as far as creating a new blog site and videos of the process.

It can be pretty devastating when you put your heart (and lots of money) into a scape just to have the aesthetics ruined by this vile plague.

SAE’s. I forgot about those. I will be visiting our LFS in the next couple of days.

Thanks again for taking the time to write this post!

Hi Benjamin,

Thanks for the insightful reply. I’d personally skip the SAE as there is no guarantee they will chow down on the stuff. I would love to read your blog though, to learn more about your battle!

Hey Ian,

Thanks for the advice on the SAE. I was definitely going to head out today and purchase one or two of these guys being that I am willing to try anything to eradicate the remainder of the BBA in my scape. I think I’ll hold out and treat the issue in other ways so I don’t have species of fish I don’t really want in my tank.

We’d love for you to take a look at our blog. There are only a few articles due to it still being petty new. Here’s the link:


Wow, I’m not sure I would be game enough to try a 50/50 combo of hydrogen peroxide and flourish excel, especially with no guidelines except “spray everything covered in black beard algae” – it sounds like a nuclear bomb.

I understand why you tried though, and I’m sorry to hear about the loss of your fish. I hope you win your battle!

Sounds like a good idea on the SAE. In my opinion, if it’s not going to eat your algae, then it isn’t a particularly exciting fish. There are plenty of other freshwater fish that I would prefer.

Thank you for such an informative article on this nuisance. I have never encountered beard algae in my 40+ years of fish keeping, until now. I followed your instructions and now have it under control.

Hi Bob,

It’s funny how these things just kind of sneak up on you, right? 40 years without even a glimpse. Then, POW… Black Beard Algae!

I’m glad to hear you found success with it’s removal.

My algae behaves like black beard algae, but it’s green; so it doesn’t look like black beard algae or staghorn algae. Can I use the same methods to get rid of my green hair algae?

Hi Megan,

If it’s green, it isn’t black beard or staghorn. As long as you are not confusing it with blue-green algae then it’s most likely green fuzz algae or green hair algae. These algaes generally appears when their is a nutrient imbalance (too much light, co2, etc.) So the first thing to do is to check your water parameters. This algae can be scrubbed off however, if you don’t get your water parameters under control, it will be back.

Regarding SAE, I’ve had great results with them but only as younger fish. They tend to develop a taste for a prefer general food you feed your other fishalf as they age.

Hi Ase,

Thanks for the feedback. That’s very interesting and even more reason not to recommend them – I’d prefer to care for a different fish than an algae eater that won’t eat algae.

I have a similar situation as above, I have what is definitely BBA growing on my pants and on one of my rocks. On the rock and threads that used to hold a long forgotten plant it looks lovely, but it is a problem for the plants. I also have an identical looking algae growing on my bogwood but in a really beautiful green. Would you recommend spot treatment on the plants to try to save the attractive species of algae or is it likely to kill it all indiscriminately anyway?

Hi Gareth,

If you are really careful, spot treatment should only kill BBA in the area that it is applied. If you really want to keep it as a decoration, I’d start by using a really small dose and seeing how it reacts – you can always up the quantity if you need.

Just be mindful that it’s possible that, over time, your BBA will spread again to your plants. If this happens you will need to spot treat again.

Thanks for the article. I am battling this big time. I do co2 injection and have what the color solution indicator say is good co2 levels, have good and strong circulation in my 55 gallon fresh planted tank and had been dosing Flourish Excel daily with no results at all. Only light the tank 7 hours per day. The only thing that has worked for me is removing rock, wood, and filters parts etc and either using hydrogen peroxide or a diluted bleach solution for a few minutes which kill it.

Any idea where my issue is given my water parameters for the fish read very good? Thank you!

Hi John,

Unfortunately there is not enough information here to pinpoint the exact problem. It could be as simple as a small amount hitchhiked it’s way in and it has overgrown from there. Spot treating with either flourish excel or hydrogen peroxide will work better for stubborn cases of black beard algae rather than just dosing the water.

You didn’t even mention the best method lol. Get yourself a spray bottle of hydrogen peroxide, when you do your water change in your tank, spray a medium amount of HP wherever the Black beard algae is. It will start to kill it almost immidiately and you will notice a difference within 24-48 hours. Hydrogen Peroxide eventually breaks down into just water so no need to worry about it harming your fish or plants.

Hi UA,

This guide is was written with beginners in mind and aims to keep things simple. I have seen beginners and experts alike accidentally nuke their tank by incorrectly using hydrogen peroxide. Your comment highlights this problem. What is a “medium” amount to you might be a small amount to someone else. If you are comfortable using HP, then go right ahead. I use it too, but I am always hesitant to recommend it to beginners.

Hi Shari,

For artificial plants you could just remove them from the tank and give them a soak in water diluted with peroxide or bleach. Since you don’t have to be careful about killing the plant, this is probably the most effective treatment for BBA.

Hi, really interested in you.saying to use bleach or hydrogen peroxide. Do you then just rinse it off and it doesnt hurt the fish? Also similarly in the other comment where you say to spray hydrogen peroxide when doing a water change as the hydrogen peroxide breaks down in the water. So would this be a total water change? or are you spraying the peroxide into the water? Are the fish still in the tank or do the fish come out for 48hrs….im very intrigued and would love to know as this algae is driving me nuts! Thank you.

Hi Melanie,

A bleach or Hydrogen Peroxide dip can be safely removed in fresh water. In fact, a bleach dip is often used on live plants prior to adding them to an aquarium – to help eliminate hitchhikers prior to adding them to your tank. Be mindful that a bleach solution can discolor some plants.

As for liberally applying hydrogen peroxide to your tank, it’s a more advanced technique that is outside the scope of my site. The focus here is on beginner friendly solutions that can be implemented with minimal risk. There are plenty of guides and videos online that show how to treat with hydrogen peroxide if you want to research it further.

Hi. I’m not sure how old this article is as it doesn’t say. I’m kind of in the same boat. But with an added extra?
I have a planted aquarium. The whole setup was running fine for weeks than within hours (over the course of one night) the gravel in my tank at the front and middle was all covered in small black fuzzy balls. I knew instantly it was algae. However there was none on the plants at all? The gravel was what it started growing on.
Over a week I noticed it did start to slowly spread as in the balls were getting bigger and even merging.

I added some Malaysian trumpet black snails to the tank and I know they don’t like constant light (which I had before I added them) the snails are mostly active in the dark so I turned the light off. Here is the snag. When I checked the next morning the same black fussy balls all turned green? Which makes me think and wonder is this actually black algae I have if so why turn green? However it makes sense now reading your comment on to much light. Everything in my aquarium seems happy enough. And the plants seem healthy.
At the front of my tank iv also noticed one more solid looking black ball shaped thing under the gravel with long tentacle like things coming from it.
I do agree with you the speed this stuff grows is astonishing.
I will be keeping your tips on hand for the future if and when I ever need them. Thank you for taking the time to post a helpful article.

Hi Dave,

How odd.

If it changes to a green color in the absence of light, I don’t believe it to be BBA at all. Even after 24 hours of darkness, blackbeard algae I have witnessed keeps it’s dark color. I am actually a little unsure what you could be dealing with. I honestly wish I could help you further.

I will add that using a day/night cycle can stop many types of algae from taking a hold and becoming established. The easiest solution is to use an automatic plug-in 24 hour timer and connect it to your tank lights.

So, I have a 900 gallon stock tank with a LARGE Alligator Snapping a turtle in it who is covered in BBA. He will soon be going on display at a local zoo and while he looks cool all fuzzy with algae, I’d prefer to let his real beauty shine through. There is no substrate and I do weekly water changes in his outdoor pool. I’m thinking about trying the liquid carbon, but once the algae is killed, does the structure remain? It’s so well attached to his shell that I can’t remove it with scrubbing, and I’m afraid I’ll end up with white beard algae “carcass” covering him which would be worse than the current situation.

Hi Kris,

Unfortunately my expertise covers fish, it doesn’t extend to reptiles. In this instance, I would suggest speaking to a vet or someone with more experience with keeping turtles. I wish I could be more help.

Turtles are constantly shedding their shell schutes. If the deal BBA does stay attached, then natural shell will eventually be uncovered. It may just take a while. Apart from that, you can also try taking the turtle out, patting dry, using a soft tooth brush with a tad of dawn dish soap to brush the shell. Rinse, then pat dry. I would then take a betadine solution to the shell and rub it on. Let dry then return the turtle to the water. I’m not sure if that would work for the dead BBA, however it is worth a shot and it’s also good to have betadine on hand for reptiles anyhow. 🙂

Really excellent article! So, I have some BBA growing on a rock (and tufts on some driftwood) where Christmas moss is just beginning to take hold. (Which was my intention) Do I need to get in there and remove the BBA or will the moss out compete it and effectively take over the rock and wood?

Hi Kathy,

It’s unlikely that the moss would “outcompete it,” especially if conditions are right for the BBA. If you want the moss to be the feature, you’ll have to remove the BBA completely.

I have a “white lobster” (crayfish) in my freshwater tank that has BBA growing on it and its antennas. Can I apply Flourish Excel directly onto my crayfish with a syringe? Will it hurt it?

Hi Christina,

I wouldn’t do this at all. Are you able to manually remove it with a toothbrush? Unfortunately, I have no experience in removing algae directly from crustaceans.

I had a problem with an overstocked tank as several of my platys had a lot of babies, abour 6 weeks ago i managed to rehome most of them which left me with 8 fish and a Raphael catfish, i did a thorough clean out and added the fish safe. etc that was needed and had a nice clean tank, about 4 weeks ago i noticed a growth on one of the ornaments and i believe it is black beard algae, i have a few ornaments in the tank but no live plants and the platys seem to be acting weird, they seem very aggressive to each other and are flitting very rapidly around the tank, unfortunately i will struggle to remove the ornament most affected as the catfish lives in it and dashes in the second any movement is made near the tank, i’m hoping i can kind of scoop it up with the suction pump, any advice will be appreciated

Hi Lynsey,

I’d test your water parameters and if everything seems normal, try removing the decoration and scrubbing it with a toothbrush and some hydrogen peroxide. Rinse and replace.

Platys should be kept in small groups with a ratio of males to female fish. If this is skewed, it’s not uncommon for them to fight. I suggest reading up a little more on this since this is out of scope of this article.

Would you recommend adding hydrogen peroxide directly into a 40 gallons tank that is infested with black agae? How much would you add?

Hi Frank,

Unfortunately, I don’t make recommendations regarding Hydrogen Peroxide – I have seen too many beginners nuke their tanks with it. There are plenty of online guides to follow if you do want to go that route, but I generally only recommend it to people who have prior experience dosing it.

We have a 30 gallon community tank that was over run with BBA. Drove me nuts. Siamese algae eaters didn’t have a prayer of cleaning it up. We recently moved and the tank was shut down for the move. I through all the live plants out trying to stop from reintroducing BBA to the newly set up tank. I had heard boiling BBA kills it so after I cleaned all the gravel I boiled it all for a while. Do you figure this killed it. Now that I know about Seachem I am gonna get some and use it.

Hi Chris,

Sorry to hear about your ordeal. It can be nasty stuff when it takes hold. While boiling the substrate will have killed the BBA attached to it, if the environment is setup for BBA to thrive, it will likely return. Killing BBA doesn’t fix the problem of it appearing in the first place. Say if there is a nutrient imbalance, it would be better to fix this first as it will deal with the cause rather than the affect.

Hi Alan,

Nutrient imbalances are typically found in planted tanks – it could be too much of one particular fert, not enough of another, too much light etc. This varies dramatically from tank to tank – the only way to know for sure is to test for it.

Fluctuating Co2 is a commonly mentioned thing for high tech tanks that have BBA. But what about low-tech tanks with BBA that don’t do water changes? On multiple times, I have fixed my BBA issue by removing dissolved organics. And that means removing detritus that builds up on the planted tank, and keeping the tank clean. For co2 injection, I do remove organics and also increase my co2 levels. If plants are getting too much light and little co2, then there’s gonna be a problem.

I spray a bit of hydrogen peroxide to plants and that has worked as good or better than Seachem excel. I’d also use Siamese alage eaters and black mollies, depending on how bad the BBA is spread.

Everyone should do good tank maintenance to avoid all sorts of alage problems.

Hi Elizabeth,

Plants do not need a full 24 hours of light. In nature, they only have the day/night cycle to go by, which leaves plenty of time for darkness.

Hi Ian,
I have read all of the posts. Im not a beginner and I feel comfortable using HP I will remove my cory from the tank while I treat. What about the others. clown Loach, tiger shark, skirt tetras, betta,dantio,pleco. Or should I remove all? It a 90 gallon planted. I keep good perimeters and weekly water changes at 25%. I currently use excel weekly. have not treated yet. Tried basic stuff. Planning on cleaning everything this weekend. thank you

Hi Tina,

Unfortunately as this site is aimed at beginners, I do not want to make any recommendations or guidance around H2O2 in case others imitate it. I have seen far too many tanks nuked. There are plenty of youtube videos and forum posts that can provide further information here.

I need to thank you so much for this article and suggestions. My tank is mature but has been plagued by black beard algae for a few months and it got worse and out of control. I bought the Seachem, unsure of what to achieve, a little dubious to be honest. Well, after 3 days, my black beard algae are already getting redder.

Thank You!

Hi Oli,

It sure can be stubborn stuff, I’m glad to hear you are finally having success with getting rid of it! Thanks for sharing your experience.

I just started having a problem with bba and am going to up my daily dose of Excel. Thank you so much for your article. Do you recommend cutting down on the ferts? I am using seachem comp and seachem root tabs together in my 20 gal planted tank. I added the plants recently, started seachem comp, Excel, root tabs and bought a light for plant growth. All these changes within 2 months. Now I have bba. Not real sure if I should change anything else other than upping the Excel. Thanks for your help.

Hi Kris,

Excellent question. An excess of nutrients (such as ferts, feeding or sunlight) is a common cause of algae. Experimenting with reducing ferts and raising the light higher could help you narrow down the cause. It’s much preferable than upping the amount of chemicals you add to the tank.

Hi just wondering if you can help me, my tank has all this black all on the glass, there’s no bba in the tank.

Hi Jillian,

Is it just slime? if you slide a credit card off it, does it slide right off? Do you regularly wipe down your tank glass? It’s possible this is just slime build up.

Hello i have a 42 gallon tank,in that there are 2 blood parrots,1 firemouth cichlid,4 glass fish,4 rosy barb,2 tiger barb,4 serpae tetra,2 silver dollers,they are quite fine together but after some days of water change my water turns greyish but still clear,i can see that after putting some water in a white bucket,in tank it is hardly noticeable,my fishes still eat food like carzy,what can i do to treat that greyish water,i have no drift wood in that.thanks in advance ????

Hi Abhishek,

That tank is probably a little small for all those fish. Otherwise, have you tried some finer filtration? It could be free-floating waste that is causing the tank to look hazey. Filter floss should do it.

I looked for all possible reasons ,i understand that 42 gallon is little bit small but i hardly notice any conflicts between fishes and they are quite happy, always begging for food like childrens,rosy barb,galss fish,tiger barb and serpae tetra are smaller species ,i have a 30 watt internal filter and it’s cleansing power is good, besides that do i have to use any conditioner ? Thanks for reply ????????i was thinking of seachem prime? Do i really need that?

Hi Abhishek,

Unfortunately, fish don’t do well at showing they are suffering. Too many fish isn’t determined by how well they get along but rather by the waste they produce. In my opinion, you will forever be having difficulties in an overstocked tank. There is no way around it.

Water conditioner is used to dechlorinate the water. If you already have a different water conditioner, then you can get by without prime.

Thanks i will move some of my fishes to other tank,after your point of view i also begun thinking of too much waste production and i think i figured it out, thanks for your time,you are really a life saver for everyone’s fishes,keep it up ????????????????i am thinking of moving silver dollers to other tank as they are underwater goats and introduce some live plants to my aquarium in pots as parrots are diggers,i have seen many aquarist having plants in pots with parrots and they are really successful,i also wanted to do the same.????????????????

I completely agree with your plan. I’m sure your aquarium will look stunning once you are done. I hope getting your stock down to a more appropriate level helps!

Interesting read, having kept fish over 35 yrs had BBA appear in1918 note Hot summer killed a lot of lawn grass, mains water changed to a different source, phosphate change? not the cause as I use 2 parts rain clean water 1 tap, soft water fish kept. how I cured it was using Christmas wrapping paper (non see through) cut out all light around tank for 4 Days, no loss of any fish, cured it Back to Nature was the best advice I was ever given. Plants washed in Milton solution baby
sterilising fluid rinse in clean water this is not as harsh to plants, throw away the bad ones hope this will help.

yours truly

Percy Vere

Excuse the Pun

Hi Henry,

That’s a very specific mix of water you are using and a fascinating solution to boot. I’m unfamiliar with using Milton solution baby sterilizing fluid. Thanks so much for sharing your solution, I hope it helps others here!

I gave up on my planted tank plagued with BBA and would like to use that tank for a saltwater quarantine tank. Can the BBA be transferred to a saltwater tank?

Hi Tiffany,

While there are algaes that look similar to BBA that flourish in salt water, they are a different type to what would have appeared in your tank. Freshwater BBA will not survive in a salt tank.

Hi Ian
Thank you for the advice regarding Flourish; It was suggested to me at the pet shop that I went to today also. My question is how does it affect clown loaches? Someone also suggested hydrogen peroxide (3%) to treat black beard algae…
Any advice would be awesome.
Kind regards Britt

Hi Britt,

While you can use h202 (hydrogen peroxide) I generally don’t recommend it to those who don’t have much experience with it. I have seen countless beginners nuke their tank with it. Flourish Excel is a little more forgiving of incorrect dosing. If you do want to go down that path, there are plenty of guides and youtube videos on it.

As for the clown loaches, anecdotally, it shouldn’t impact them if dosing correctly. A member of my local fish club has clown loaches and he uses flourish excel.

I just got threw trimming my plants and soaking my decorations/rocks. Dipped my plants in hydrogen peroxide. Also filled my canister filter with it. Put everything back together. I wouldn’t add it to my tank water, but it killed it. Looked like snot stuck on stuff. Washed off most off it and the fishes started pecking at the rest that I couldn’t get off. Simple easy inexpensive treatment. I am going to start adding Excel to my tank though, sounds like a great long term preventative, but dipping new plants in peroxide Before adding them to my tank is going to be my new regiment. Hope to not have to go threw all this again.

Hi Kera,

That sounds like a fantastic plan. I Cannot recommend soaking plants in hydrogen peroxide enough, it solves mot problem before they are introduced in your tank!

I added about 35% extra of Excel because I miscalculated the volume of my new 160 litre / 42 US G, and it/I killed 13 of my fish over a painful 48 hour period and that, too, as I had replaced half of the water within 2 hours of adding the Excel as I realised my error.

I wonder what prompts you to exclaim, “Flourish Excel is a little more forgiving of incorrect dosing.”!

I wonder what is a “little” and what is not a little!


Hi Rahul,

I’m sorry to hear what happened to your fish. As for forgiving, It’s all relative, compared to using H2O2, Flourish excel is absolutely more forgiving. An overdose won’t nuke your beneficial bacteria. Overdosing with most chemicals will have negative consequences.

Also kills ricca and subwasertang. So don’t use it if you have these in your tank. Wish these authors would mention that when they right these things.

Hi Martha,

With so many different fish and plant species that can inhabit aquariums, it’s unrealistic to list every interaction. I would hope that anyone would do their own research before adding chemicals to their tank.

I am excited to say that I have figured a way to control it. The majority of my BBA is on my rocks, appliances, etc. I took the fixture out of my aquarium, soaked it in bleach, rinsed it well and set it over a hot air vent for a few days. After it dried, I picked that crap off and used a tooth brush for the rest. Now if I could keep it out of my filter I could live with it. This will only work for removable items of course….

Hi Sabrina,

That’s fantastic to hear that you found a way around BBA, it can be very stubborn to get rid of. Thanks for sharing your experience, I’m sure it will help readers here who are looking for a different method to get rid of BBA.

Good evening everyone,
I’m delighted to report that my bba has taken to a very fast death! I have been searching for a remedy for months/years until I heard of the spotted siamese algae eater! I have a 400l juwel aquarium that’s been running for over 10 years and slow but surely the bba moved in! I purchased five siamese algae eaters ten days ago and they have munched 90% away. Old bba algae has vanished from all my mopani wood and my many anubias have broken into life too! Great fish well recommended.
All the best

Hi Chris,

Congratulations on your success in defeating black beard algae. With that many Siamese algae eaters, you can be sure it won’t be returning as well. Thank you so much for sharing your experience!

Hi Ian,

I’m over here now while dosing to kill off the Planaria.

I had made many changes at the same time over the holidays and they probably brought both the worms and BBA. I added CO2 injection, High light, and ferts while doing a major rescaping.

I added some plants that need the high light, but am ok to lose them if need be.

Do you think it makes sense to stop the fertilizing to start, do a black out, both?

I also wonder about using Excel while I’m poising the worms. Should I hold off until a water change or 2?

thanks again and again. Your site is awesome and you are a great educator!

When you say high light, are you leaving the lights on too long? Even high light plants should only need up to 8-10 hours of light? It’s more the amount of lumens that is important rather than the duration for high light plants. If you are running your lights longer, consider dropping them down to the 8 hour mark. The good news is that you shouldn’t have to lose the plants to beat this.

If I was in your shoes, I’d tackle one problem at a time, the first being the planaria. Hopefully the Safe-Guard does it’s job and you can move on to this.

For BBA, I’m a big fan of spot treating, I think it’s the superior method, since black out methods often have mixed results, especially given you have plants that need light. Spot treating with either Excel or hydrogen peroxide (h2o2) would be the preferred choice. If going the hydrogen peroxide route, watch a youtube video or two first, I have seen many beginners accidentally nuke their tank and is why I recommend excel instead.

Thanks so much for the kind words, I hope you can overcome these difficulties!

If one has black beard algae starting on driftwood, any reason one couldn’t pull the wood out, drip the Flourish Excel on it while it’s out, set it in a bucket for 10-15 minutes, and then put it back into the tank?

Hi Kathy,

For an isolated piece like driftwood, if you can remove it then this is by far the easiest option. You’ll know it’s dead when it begins to turn a pink color, however, this may not be evident until you return it to your tank.

I’ve learned just bleach that bad boy. You can do on live plants as well just make sure you dont get the roots in the bleach. Mix with water and hold in for a few seconds. On decor and driftwood you can leave in longer and you’ll see the change in color of the algae right then. Make sure to wash off the bleach before putting back in your tank. Really works and doesnt harm fish or plants if done right. And everyone has bleach :).

Hi Turk,

Yep, bleach is another solution but it’s more dangerous than Excel or H2o2. If a beginner doesn’t wash it off properly then you can crash your tank. But I’m glad to hear it works for you!

Hi Allan,

You are going to need to be more specific here. When someone refers to “black algae” they are typically just referring to it’s color. A lot of algaes fall under this umbrella.

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