Black beard algae: ten ways to target it

1. Cut the light

BBA thrives when light is strong or inconsistent. Reduce your photoperiod to 6–8 hours and avoid direct sunlight. Use a timer so the schedule is stable. Many tanks see BBA fade once light is dialled back.

2. Stabilise CO₂ (if you use it)

In planted tanks with CO₂, swings between high and low CO₂ can favour BBA. Keep injection steady — same time, same rate — so plants outcompete algae. If you don’t use CO₂, skip this; focus on light and nutrients.

3. Lower nutrients

Excess nitrate and phosphate feed algae. Cut back feeding, do regular water changes, and avoid overstocking. Test and log (e.g. with App-aquatic) so you see trends. See how to lower nitrate.

4. Manual removal

Pull or trim affected leaves. Scrub decor and hardscape. Siphon out what you remove so it doesn’t break down in the tank. You won’t eliminate it by hand alone, but you reduce the load and buy time for other fixes.

5. Spot treatment with liquid carbon

Glutaraldehyde-based liquid carbon (e.g. Excel, Easy Carbo) can be applied directly to BBA with a syringe or pipette. Turn off the filter briefly so it doesn’t dilute. Use as directed; overdosing can harm fish and plants. Works best with manual removal and better light/nutrient control.

6. Remove and treat decor

If wood or rocks are covered, take them out. Scrub, soak in diluted bleach or hydrogen peroxide (rinse thoroughly before returning), or boil wood. Reintroduce once clean. Prevents spores from spreading.

7. Improve flow

BBA often settles in dead spots. Adjust filter output or add a small powerhead so water moves evenly. Stagnant corners and behind decor are prime spots; better flow can slow regrowth.

8. Add grazers (with caution)

Siamese algae eaters (true SAE, not flying fox) and some shrimp will nibble BBA, especially when it’s young. They won’t clear a bad outbreak alone. Match species to your tank — see cleanup crew.

9. Blackout (for severe cases)

Cover the tank for 2–3 days: no light, no feeding. Do a water change before and after. This can knock back algae but stresses plants. Use only if other steps haven’t helped and you’re prepared to support the tank afterward.

10. Fix the cause, not just the symptom

BBA keeps coming back if light, nutrients, or CO₂ stay unbalanced. Spot treatment and manual removal help short-term; long-term control means consistent light, feeding, and maintenance. Track your routine so you can adjust.

Quick takeaways

• Reduce light and stabilise CO₂; lower nitrate and phosphate.
• Remove manually; spot-treat with liquid carbon if needed.
• Improve flow; add grazers as support.
• Address the underlying cause so BBA doesn’t return.