Troubleshoot
Staghorn Algae: Causes & Fix Order
Staghorn algae grows as grey-green or reddish antler branches on hardscape and slow leaf edges. It is closer to BBA in causes (unstable CO₂, organics) than to soft hair algae.
- Staghorn
- Antler tufts
- CO₂ / organics
- Spot + stability
What you’re seeing
Branching tufts that look like tiny antlers—often grey-green, sometimes rust-tinted. Firmer than hair, less jet-black than classic BBA. Check the ID chart before you treat.
| Pattern | Likely driver |
|---|---|
| Antlers on wood + filter outlets | Unstable CO₂ / flow edges |
| After dirty filter or melt | Organics |
| Jet-black short brush | BBA |
| Long green strings | Hair algae |
Likely causes (ranked)
Unstable injected CO₂
Same niche as BBA: daily pH swings and dead edges.
Quick test: Drop checker not a steady green.
Organics on rough décor
Melt and dirty intakes seed antler tufts.
Quick test: Mulm on wood grain.
Light on slow hardscape
Open wood under strong LEDs without stem competition.
Quick test: Few stems, bright hardscape.
Spot-treat only
Tufts bleach then return if CO₂/organics stay messy.
Quick test: Same antlers in 7–10 days.
Fix order
-
Step 1
Stabilize CO₂ and flow
Steady injection during photoperiod. Aim flow across hardscape edges. CO₂ hub.
-
Step 2
Cut organics
Siphon, rinse mechanical media, trim melt.
-
Step 3
Remove tufts
Pull/brush antlers off wood. Trim coated leaf edges.
-
Step 4
Spot liquid carbon
Treat remaining branches on décor—filter off briefly. Then hold parameters 2 weeks.
When to escalate
- Jet-black brush instead → BBA fix order.
- Woolly green blanket → Cladophora.
- Still exploding after stable CO₂ → check photoperiod and planting density.
Helpful products
Related guides
- BBA fix order — Sister problem
- Hair algae — Don’t confuse
- CO₂ hub — Stability
- Algae ID chart — Compare
FAQ
Is staghorn just another name for BBA?
Hobbyists mix them. Staghorn is branching grey-green/red; BBA is darker short brush. Causes overlap—CO₂ and organics.
Will SAE eat staghorn?
Unreliable. Don’t stock fish as the primary cure.
Does lowering light alone work?
It slows growth; established antlers still need pulling + CO₂/organic fix.
Same treatment as hair algae?
Hair is mostly photoperiod + pull. Staghorn needs CO₂ stability like BBA.
How long to clear?
Clean new growth in 1–3 weeks if injection is steady; old tufts need removal.
Safe for shrimp?
Mechanical + stable CO₂ yes. Spot carbon away from shrimp; never copper.
Aqua Plants Hub Editorial
