Black beard algae, also known as brush algae, is part of the red algae family and grows on plants, on the edges of their leaves. It also grows on hard surfaces. The algae have this name because of the hair-like strands kind of resembling an overgrown blue-green beard. It stubbornly clings to aquarium plants, rocks, wood, and, well, practically anything it attaches itself to and is difficult to remove by hand. This nasty little stuff has become a scourge for fishkeepers over the years.

A few fish eat this stuff, but not many (the Siamese Algae Eater and the Florida Flag Fish), so it’s definitely not going to just “go away” in a stocked pond or aquarium.

So, let’s take a look at what it is, what it does, and how aquarists can deal with it in your aquariums.

How to Identify Black Beard Algae

Black Beard Algae has the look that you would think just from its name. When this alga begins to grow, it looks like your aquarium is growing black stubble across the tank. If you allow it to keep growing in your tank, then it will grow and look like your aquarium has grown a full length and blowing black bead.

This alga is also known by other names. It is called black brush algae or simply BBA.

Most Black Beard Algae variants are found naturally in saltwater.

When Black Beard Algae infects a tank, the stubble will first appear on the edges of live plant leaves and then will quickly cover the leaves. Your plants will begin to die because they have no direct access to the sun and so they can’t photosynthesize.

Common Causes of Black Beard Algae?

One of the main ways that Black Beard Algae can start growing in a tank is due to either an unstable or very low level of carbon dioxide. When the CO2 is unstable, plants are unable to properly use nutrients from fertilizer or able to properly process light for photosynthesis.

The best way to solve the problem of your aquarium having low or unstable levels of carbon dioxide is by using CO2 supplements. Be sure to avoid overdosing, though.

The most frequent way that Black Bear Algae becomes introduced to the tank is through plants that are contaminated with the algae. However, it is possible for small free-floating strands of the algae can be transported with a fish that you purchased. Those strands are enough to cause an outbreak of the algae.

CO2 Issues

If you are looking for the primary reason a tank has an out-of-control growth of Black Beard Algae, look no further than the CO2 levels of your tank. If a tank has insufficient or fluctuating CO2 levels then there is an environment ripe for growing algae. All of this can also be exacerbated by your aquarium having poor water circulation.

As you start to try and combat the Black Bear Algae, your priority should be to bring the CO2 levels up to the levels they should be. The easiest way to add CO2 is by using an injected form of CO2 that outs it directly into the tank water.

Too Much Light in the Aquarium

Practically everything living in your aquarium loves light, this includes algae. Part of what makes algae such a problem is that it is very efficient at absorbing aquarium light to fuel its rapid growth. The longer algae have access to light the faster they will grow in your tank. If you already have growth lights for your plants, this will make the problem worse.

One valid method of killing the algae is to deprive it of extra aquarium light. If possible, you can shorten the hours that the light is on or even go as far as to cut off light altogether for a few days.

Does Black Beard Algae Hurt Fish?

While Black Beard Algae can easily kill plants in your aquarium, the algae are unlikely to harm any snails, shrimp, or fish that you keep.

However, this does not mean you should simply relax and let the algae grow. It takes little time for it to cover all the plants like anubias and surfaces of your tank. Not only will your tank look filthy and disgusting, but the longer you wait to solve the problem, the harder it will be to get rid of the algae.

If you let the Black beard Algae spread and cover the entire tank, eventually there will be an imbalance in nutrients that can lead to your tank becoming unsafe for your fish, and potentially leading to illness or death.

Does Black Beard Algae Hurt Plants?

Black Beard Algae will kill your plants if it is allowed to spread unchecked. While this alga doesn’t kill the plants directly by toxins or leaching from the plant, instead the algae kill by smothering your plants to death.

If you see a spot of black beard algae, it is a big deal. It is important to immediately take steps to correct your tank’s imbalances because the speck will soon grow to cover the whole plant.

When your plants are covered, they can no longer absorb light through photosynthesize. The Black Beard Algae also will compete with your plants for nutrition in the water and soil, further starving your plants to death.

How to Get Rid of Black Beard Algae

There are several methods for getting rid of black beard algae.

Treat the Tank With Hydrogen Peroxide

In some situations, it’s simply impractical to remove the affected items from your tank, so you have to treat the whole tank instead. One of the ways you can do this is by adding 10 milliliters of neat 3% hydrogen peroxide per 15 gallons of aquarium water.

  1. Add the appropriate amount to the tank
  2. Repeat once a day for 3 days, then wait.
  3. If the algae isn’t gone within 14 days, repeat the process with a little higher dosage.

This method is safe for fish, shrimp, et cetera.

Regulating Phosphate (PO4) In Your Aquarium

When substances like uneaten food, waste produced by the fish, or dead plants are allowed to rot in your tank, it builds up the level of phosphate in the tank and enables the algae to not just survive but thrive in this environment.

To prevent a rise in phosphate make sure your aquarium is clean.

Introduce Black Beard Algae Eaters

Specific fish species and snails love to nosh on black beard algae, so one option for getting rid of it in your fish tank or pond is adding some of those fish species into your stock. They won’t eat a ton of the algae, but they will definitely eat enough to make a dent in it if it’s not too bad and may help reduce the likelihood of the algae returning later on in larger portions.

Some of the species of fish for planted tanks that love to nibble on this algae include:

The main thing to remember is that these species won’t eat the algae unless they don’t have anything else to snack on. Avoid overfeeding them (for their health and for the algae reduction) and keep an eye on their movements to make sure they’re not getting lethargic.

Boost Carbon Dioxide Level In The Aquarium

Carbon dioxide won’t directly kill black beard algae, but it can help to reduce the amount of it in your freshwater aquarium. CO2 promotes plant growth, which reduces the nutrients algae can leach out of the water, thus reducing the availability for algae growth. Doing this basically means you’re letting your plants outcompete algae for growth.

You can increase CO2 levels in a few ways – CO2 injection, heat treatment, and liquid carbon.

How to Prevent Black Beard Algae from Forming

To stop an algae problem in your fishkeeping world, your best course of action is to practice prevention in the first place. When this alga begins to grow in your tank, it will grow rapidly and can cover everything in the aquarium that doesn’t move. It will kill plants by blocking the light and preventing the process of photosynthesis from happening.

Not only is this algae difficult to stop and get rid of if your aquarium has been infected once, but it is also easier for the algae to come back again.

One way Black beard Algae can enter your tank is by introducing new fish. One of the best ways to prevent Black Beard Algae from entering the tank is to ensure you are buying your plants and fish from a reputable store. Even if you trust the person you buy your fish and plants from, it is important to still quarantine because of how easy it is for this algae to spread.

The way to avoid new fish bringing in potentially deadly fungus or algae is by quarantining new fish for at least two days. When placing the fish into the quarantine tank, it is important to make sure that you use a net to place them in. Do not just dump them out of the bag because it’s unpleasant for the fish and you may be dumping in water that could contain things that will destroy your tank’s water quality.

Be sure to conduct weekly water changes regularly, as well, to help reduce the build-up of things that attract algae. You should also clean the substrate regularly with a vacuum, along with keeping driftwood, lie plants, and other aquascaping features cleaned. Be sure to keep your filter media cleaned appropriately, as well.

Plants can be another way that dangerous Black Beard Algae can be introduced to your tank. When you buy new plants, soak them in the plant prophylactically which is mixed with a ten percent bleach solution. The plants need to be submerged for about two to three minutes.

Another option is to clean the plants by using a hydrogen peroxide bath. This chemical is less harsh than bleach but can also kill and bacteria, parasites, or diseases that may be on the plants.

One last note, make sure you do not take any wild plants or animals and just put them in your tank. Taking them away will not just damage the ecology, but you have no idea what may be on the wild plants and animals.

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