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Black beard algae, or BBA, forms dark grey to black tufts on plant edges, wood, rocks and equipment. It's tough, clings tightly and most algae eaters won't touch it. The good news is that once you fix the cause, it can be cleared.
How to identify black beard algae
- Short, dark, brush-like tufts, often on the edges of slow-growing leaves
- Grows on wood, rocks, filter pipes and outlets
- Feels rough and is very hard to wipe or pull off
- Can turn red or pink when treated with liquid carbon or bleach (a sign it's dying)
What causes black beard algae?
BBA is a red algae that thrives when conditions are unstable, especially carbon dioxide (CO2). The most common causes are:
- Fluctuating CO2: injecting CO2 inconsistently, or CO2 that's too low for the light.
- Too much light for the plants and CO2 available.
- Poor flow leaving dead spots.
- Organic waste from overfeeding, overstocking or infrequent maintenance.
- Old, slow-growing leaves that give it a place to settle.
How to get rid of black beard algae
1. Remove what you can
Trim badly affected leaves and scrub wood and rocks outside the tank. Use algae pads and scrapers on glass and equipment.
2. Spot treat with liquid carbon
Turn off the filter, then use a syringe to apply a liquid carbon product directly onto the algae at the normal dose for the tank. Wait 15 minutes, then turn the filter back on. Within a few days the algae turns red or pink and then dies off. Take care with sensitive plants such as vallisneria and some mosses.
3. Fix CO2, light and flow
- If you inject CO2, make sure it's stable and reaches the right level when the lights come on. Read how to dial in CO2 and see our CO2 sets.
- Cut the light period to 6–8 hours. See lighting schedules.
- Improve flow so there are no dead spots.
4. Keep plants healthy
Fast-growing, healthy plants outcompete algae. Dose a balanced fertiliser such as Tropica Premium or Tropica Specialised and add more stem or floating plants.
5. Keep up maintenance
Do weekly water changes of 30–50%, clean filters, and vacuum the substrate with a gravel cleaner. Don't overfeed.
What eats black beard algae?
Few fish eat BBA. The best are young Siamese algae eaters, and some keepers report success with Amano shrimp and Florida flagfish. Algae eaters help, but they won't fix the cause on their own.
Browse our algae management range and read our complete guide to controlling algae.
