Black Beard Algae: Identify & Destroy It In Only Days

Black beard algae which is more commonly referred to as brush algae, because of its soft, furry and slippery nature is an algae plant in the red algae family. This algae commonly grows in dense patches, mostly on surfaces and plants in an aquarium.

Black beard algae is blackish green in color compared to its other red algae family. Its stubborn nature allows it to cling onto the hard surfaces on the aquarium or the plants, thereby making it difficult to eliminate by hand.

The algae isn’t necessarily harmful to most of your aquarium inhabitants, there are some fish that actually consume it. This includes Siamese Algae Eater and Florida Flag Fish.

How To Identify Black Beard Algae?

Black beard algae looks exactly like it sounds. It starts off looking like black stubble, which if left unchecked will develop into a long flowing black beard. It’s often also called black brush algae, or even just its initials, BBA.

Most black beard variants are saltwater, however, I most often see it in freshwater tanks. It’s extremely common. If you find your tank overtaken by alga, chances are its black beard.

Images speak louder than words, so if you take a look at the picture below, you’ll see black beard algae just starting out. It looks very much like small spots of fuzzy stubble.

With enough time, BBA will turn into flowing manes of black hair. There’s more hair in the picture below than I have on my head.

Black beard algae will typically start its life on the edges of plant leaves, before eventually completely enveloping them.

BBA shouldn’t be confused with staghorn algae. Staghorn tends to have a wiry appearance and branching algae strands. While BBA will have single silky smooth strands. The picture below shows staghorn, which initially looks similar, studying it closer reveals a different structure.

What Causes Black Beard Algae?

The primary cause of a black beard infestation is from contaminated plants, decor items or substrate introduced into the aquarium.  Coupled with an aquarium with reduced carbon dioxide levels and too much light will allow black beard algae to grow uncontrollably.

Left unchecked, black beard algae will very quickly take over any surface it can get a hold of.  Additionally, it is important to note that the beard algae spreads quicker in unattended aquariums.

Aquarium keepers should ensure that there is balance in the tank in terms of light, nutrients, and carbon dioxide levels, as well as maintaining regular water changes. Ensuring this will eliminate the breeding habitat for any unwanted algae.

C02 & Black Algae

Unstable C02 levels are one of the leading causes of black beard algae growing unchecked.

If your aquarium has inadequate water circulation, or if your CO2 levels are not at a sufficient level, or the levels fluctuate, then that’s creating an environment that’s perfect for algae growth.

Adding sufficient C02 to your aquarium in order to reach the correct level should be your number one priority. If you’re using injected C02, your canister might be running low, or you’re not injecting the right quantity.

However, if you’re not running a C02 injector, then you may need to look at other methods of adding additional C02. A major water change can be enough to seriously impact your C02 level, so this might have been what is causing the outbreak of black beard in your tank.

If this sums up your current situation, and you have an aquarium with live plants, then I would suggest adding liquid carbon. I’ve used a couple of different brands, and Seachem Flourish Excel is still the best I’ve come across.

It’s a form of “liquid carbon” which is very simple to add to any aquarium. While it won’t necessarily raise carbon levels in your tank by any measurable amount, it still works against algae, and I’ve used it to successfully kill black beard algae.

To Much Light Is Bad

Almost everything that lives in an aquarium loves the light, but probably nothing likes light as much as algae. The more light you have in your aquarium and the longer its on for, the faster algae will spread through your aquarium once it gets a foot in the door.

If you like to grow live aquarium plants, then that fancy grow light is not only helping your plants grow but its also helping the algae bloom.

If you never turn off your aquarium lights (it does happen), or if you leave your lights on from dawn until dusk, then you’re inviting algae to take hold of your tank.

Cutting back on the time your aquarium light is on, or even choosing to leave your light off for a couple of days can stop black beard algae in its tracks and even kill it.

I would suggest employing an automatic timer to properly regulate the time your lights are on for. If you choose to manually control your lights, then it’s something that easy to make mistakes with. If you use a timer, then you really need to be religious about switching your aquarium lights on and especially off.

Aquarium timers are fairly inexpensive and can save you a ton of time and expense, so they are worth checking out. I like this one.

Can Black Beard Algae Harm Your Fish?

The simple is no, black beard algae in your aquarium is unlikely to harm any of your fish, shrimp or snails.

However, in as much as it is not harmful, the unwanted black substance clinging to all of your plants, and surfaces is pretty unsightly. Additionally owing to its stubborn nature, it is highly likely to spread through the aquarium and cover the whole tank is left unchecked.

This could ultimately cause an imbalance in nutrients and lead to an unsafe environment for your fish. Eventually, the tank will become harder to maintain, clean and could lead to increased levels of harmful chemicals.  Your fish will ultimately suffer as the algae takes over the aquarium reducing the livable space.

Can Black Beard Algae Harm Your Aquarium Plants?

On the other hand, the presence of beard algae in the aquarium may kill any plants contained in your tank.

The algae won’t kill your plants directly, it won’t release toxins or leach nutrients from the plant. Instead, it’s a slow smothering.

If you spot on spot of black beard algae, it’s not big deal.  But when the algae starts to cover the whole plant, then that’s a different matter.

Your plants will no longer be able to photosynthesize, which as you can imagine is bad for your plants.  Additionally, there will be additional competition for nutrients.

Both of these factors will compound and lead to your plants dying off.

How to Get Rid Of Any Black Beard Algae in an Aquarium

Black beard algae is an awkward and slimy pain in the backside, making it nigh on impossible to remove by hand.  Thankfully there are a number of methods we can employ to eradicate black beard algae from our tanks permanently.

So, how can you get rid of black beard algae in an aquarium? There are several methods for removing black beard algae.  One of the easiest and most effective is using 3% hydrogen peroxide, use 10 ml per 50 liters (15 gallons). Adding once a day for 3 days and monitoring the black algae until it dies off.

For alternative methods and more information on preventions and identification, please read on 🙂

Treat Black Beard Algae With A Hydrogen Peroxide (H2O2) Bath

Hydrogen peroxide (only use 3%) is a widely available over the counter product. Aquarium owners are advised to have this chemical to hand to treat a number of conditions that can affect the inhabitants of a tank.

For the Hydrogen peroxide to work, you are advised to completely soak any affected décor or plants (alive or artificial) that has algae for roughly three minutes in undiluted 3% hydrogen peroxide.

Once the items have been soaked for long enough, then thoroughly rinse the items in fresh water. This is an easy procedure to perform as long as you can remove any affected items from the tank.

If you can’t remove all the items affected the algae outbreak, then you may have the use this method in conjunction with some of the other methods discussed below.

Treating A Tank With Hydrogen Peroxide

When it’s just not practical to remove all the affected items from your tank to treat them individually, then consider treating the whole tank instead.

I’ve successfully annihilated a black beard algae infestation in under 14 days using this method.  The tank wasn’t my own, but we managed to do it without adversely affecting any of the fish.

Our method used 10mls of neat 3% hydrogen peroxide per 15 gallons of aquarium water. For example, you would use 10mls for a 15-gallon tank and 20mls for a 30-gallon tank etc.

Add the appropriate amount of Hydrogen Peroxide directly to your aquarium in an area with plenty of water flow. Repeat this once a day for 3 days and then wait.

After a few days, you should start to see the black beard algae change color and fade.  After a month the algae should have died off completely.  If it hasn’t you may need to repeat the process with a higher dosage.

Your plants may fade ever so slightly during this process, but they should otherwise remain unaffected.

Your other aquarium inhabitants, such as fish, shrimp, and snails should be completely unscathed.  However, if you’re worried about them, then move them to another temporary holding tank while you deal with the algae issue.

Regulating Phosphate (PO4) In Your Aquarium

Decayed substances in your aquarium develop phosphates that help algae to breed in the aquarium. These substances can come from waste products produced by your plants (dead leaves), fish waste or any other organic waste.

In addition, if you’re feeding your fish too much food, leftovers may decay and develop into phosphates.

When dealing with such possibilities, an aquarium keeper can prevent such issues by maintaining the tank.

  • Remove dead plant material as soon as possible.
  • Remove any dead fish, snails or shrimp
  • Avoid overfeeding your fish
  • Perform regular water changes

A quality aquarium filter will also go a long way to controlling the phosphate levels in your tank.  When buying a filter, make sure it has enough water flow for the size of your tank, and bear in mind it’ll take a while to establish beneficial bacteria.

Introduce Black Beard Algae Eaters

Some species of fish, shrimp, and snails can consume black beard algae.  While they might not be enough to get rid of a substantial amount of algae, they may help control it in the first place.

I would recommend trying some of the following to help control the algae from taking over:

  • Siamese Algae Eaters
  • Florida Flag Fish
  • Amano Shrimp
  • Cherry Shrimp
  • Ramshorn Snails

Just bear in mind, many of these species will only eat algae if there’s nothing better on offer.  So, if you’re overfeeding your fish, chances are all of the above will be much more likely to chow down on the fish flakes rather than the algae.

Boost Carbon Dioxide Level In The Aquarium

Carbon Dioxide doesn’t directly kill black beard algae, but it will help reduce its presence indirectly.

CO2 works by promoting plant growth, which in turn reduces the available nutrients available in the tank for algae growth.  You’re basically allowing your plants to outcompete the algae growth.  If you don’t have live plants in your aquarium, this method is unlikely to work for you.

CO2 levels in a tank can be increased with a couple of methods:

CO2 Injection

There are a number of products that will allow us to inject and diffuse carbon dioxide directly into the tank.  These range from basic $10 aerosols, all the way up to pressurized cylinders costing hundreds of dollars.

You can check out our article on CO2 injectors to get an idea of the type that will best suit your tank and your budget.

Seachem Flourish Excel (Liquid Carbon)

Seachem Flourish Excel works to kill algae in a slightly different manner compared to CO2 gas. It contains a chemical called Glutaraldehyde which is a type of herbicide, it kills black beard algae directly.

In large enough quantities it can and will kill your tank plants, fish, snails and shrimp, so always follow the instructions and don’t overdose your tank.

I’ve had great success using Flourish Excel to treat black beard algae.  However, its ability to increase the CO2 levels in a tank is debatable.  But this is probably a discussion to have another day.

Use Heat Treatment

If you’re keen to use a chemical-free approach to combating black beard algae, then heat is an option worth considering.

You’re essentially going to boil any algae infested ornaments or artificial plants. So, it should go without saying, but just to be clear, this won’t work with live plants!

Remove as many algae covered items as possible, and add them to a pot.  Now, you can either pour boiling water over everything and allow it to cool off.  Or you can boil everything on your stove for 10 minutes, which should be enough time to kill anything living.

If you have plastic plants, then boiling them on a stove might not be a great idea.  But any ceramic items should be fine.

Be wary of boiling stones, porous rocks may explode when heated!

How to Prevent Beard Algae

Prevention is, of course, better than any cure.  I would much rather take some precautions to prevent algae growth rather than taking extreme measures to get rid of it.

Moreover, the chances of being susceptible to a recurring of beard algae in your aquarium are higher if you’ve had it once. The following steps can be carried out to prevent almost any sort of algae outbreak, not just black beard.

  • Quarantine new fish and don’t allow the water they came in to mix with your aquarium water.  This is most effective at preventing disease or parasites, but it may go some way to reducing the chances of some algae breeds from being introduced into your tank.
  • Clean new plants with a hydrogen peroxide bath.  We know it can be very exciting to add a new plant to your aquarium. But, we strongly suggest treating them with a hydrogen peroxide bath before adding any new plants.  This will help prevent algae as well as a host of other parasites and diseases.
  • Only use plants and fish purchased from reputable stores. Most fish stores will have protocols and established methods for preventing transferring hitchhikers to customer aquariums.
  • Never take plants and animals from the wild. Not only would that be ecologically harmful, but you never know what might be lurking in or on them.
  • Monitor your light levels and don’t allow your lights to stay on for too long.  An abundance of light will almost guarantee black beard algae.
  • Plant live plants to give black beard algae some competition for nutrients.  Not only is this great for the health of your fish and the plant ecosystem, but it can go a long way to preventing all sorts of algae growth.
  • Perform regular water changes.  You should be carrying out a 10 – 30 % water change every 1 – 2 weeks.  If you’re not, then you need to start doing this asap.
  • Use a filter that is powerful enough for your aquarium.  A filter will ensure a sufficient flow of water around your tank and help regulate phosphate levels.  It’s a must regardless of the type or size of aquarium you have.
  • Carb up.  Don’t add pasta to your aquarium, but make sure your aquarium has enough CO2 content.  Seachem Excel can be used to combat black beard algae, and it’s even better if used as a preventative.


Leave a Reply

Your email address will not be published. Required fields are marked *