Black beard algae

Black beard algae, often shortened to BBA, is a tough, dark red to black algae that grows in short, bristly tufts on hardscape, filter outlets, slow-growing leaves and equipment inside a planted tank. It is one of the more stubborn algae types to remove once established, since it attaches firmly to surfaces and resists the light trimming that clears many other algae types.

BBA is commonly linked to unstable or insufficient CO2 levels, particularly fluctuating CO2 rather than a low but steady level, along with areas of poor water flow where debris and organic matter can build up. It tends to appear first on slower growing plants, driftwood and filter intakes rather than on fast growing stem plants, which suggests flow and stability issues as much as raw nutrient levels.

Manual removal, either by trimming affected leaves or scrubbing hardscape, combined with stabilizing CO2 injection and improving flow around the tank, is the usual approach to bringing an outbreak under control. A common mistake is treating BBA only by increasing algae scraping effort without also addressing the CO2 stability or flow problem behind it, which leaves the algae free to return as soon as scraping stops.