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Posted by @Chris_Lewis · 14h ago
Black beard algae — those dark, bristly tufts on leaf edges, hardscape, and equipment — frustrates a lot of planted-tank keepers. Here's what actually clears it.
Understand the trigger. BBA thrives on unstable or low CO₂ and excess light relative to what your plants can use, often alongside built-up organic waste and poor flow. Chasing it with a single "algae killer" rarely works; you fix the conditions.
The plan that works:
- Cut the light to 6–7 hours on a timer and reduce intensity if it's high. Light you're not "paying for" with CO₂ and nutrients feeds algae.
- Stabilize CO₂/carbon. If you dose liquid carbon, dose consistently. Fluctuating CO₂ is a top BBA cause.
- Spot-treat. Turn off the filter, and with a syringe apply liquid carbon directly onto the BBA; it turns red/grey and dies, then gets eaten or brushed off. (Caution: Vallisneria, mosses, and some stems can melt from liquid carbon — go gentle.)
- Improve flow and reduce organics. Boost circulation, clean your filter, and do consistent water changes to strip the dissolved organics BBA loves.
- Recruit cleanup help. Amano shrimp and Siamese algae eaters (true SAEs) actually graze BBA.
It won't vanish overnight — affected old leaves usually need trimming — but stable conditions stop new growth.
Your turn: post a photo plus your light, CO₂/fert routine, and water-change schedule, and we'll pinpoint which lever to pull first.