This is a first in a series on understanding algae that commonly plague our aquariums. We kick off the series with the infamous Black Brush Algae a/k/a BBA.

Black brush algae (BBA) is one of the toughest algae to get rid of in the aquarium. It’s tenacious and can overtake and suffocate your plants in a matter of a couple of weeks if not controlled.

It belongs to the Phylum Rhodophyta (Greek meaning, red plant) that includes 5,000 to 6,000 species of mostly multicellular, marine algae. There are 164 freshwater species mostly in the genus Lemanea and Audouinella.

Black brush algae (BBA) is stiff bristle-like branched or unbranched similar to a coarse horsehair. You can recognize it in tight tufts on hardscape and will line the edges of your plant leaves. It’s also known ask black beard algae because it resembles coarse beard hair.

It’s blue-green to olive to dark grey in color when young. It’s typically found in fast-moving streams where it’s ability to anchor itself comes in handy. Unfortunately, that same ability makes it extremely difficult to remove.

Easy. It hitchhiked in via plants or even in the guts of fish or inverts. Once the spores are in, they can reproduce quickly under the right conditions.

Yes, but this isn’t specific to BBA. Inconsistent or deficient CO2 will cause an imbalance in the golden equilibrium that will cause any algae to grow, not just BBA. So, although this is widely thought to be a cause of BBA outbreaks, it’s not totally correct.

Well, that’s an interesting question. There’s a great thread on this at the UKAPS, entitled What exactly causes BBA? Part 2 - Bacterial imbalance.

Here’s the summarized version: High organics in the aquarium cause heterotrophic bacteria to grow exponentially and outcompete the common nitrifying bacteria that we’re used to. Heterotrophic bacteria will result in an increase in vitamin B12 as a byproduct and a decrease in O2 further limiting nitrifying bacteria.

Black brush algae (BBA) uses B12 to grow and the decreased nitrification causes an excess of ammonium that algae use to grow.

Problems with this theory:

It is my opinion that, just like any algae, an imbalance in the golden equilibrium is what causes algae outbreaks. So, first and foremost, it is critical to rebalance the golden equilibrium.

Known methods to control black brush algae (BBA)