Troubleshoot
Cladophora / Blanket Weed: Identify & Remove
Cladophora (“blanket weed”) is a tough, branching green mat that feels coarser than soft hair algae. It clings to hardscape and plant bases. Pulling + lowering light beats chemical baths.
- Cladophora
- Blanket weed
- Tough filaments
- Pull + light
What you’re seeing
Coarse green clumps that don’t twirl off as easily as hair. Often a “wool blanket” on wood, filter cages, and Anubias rhizomes. Staghorn is darker/redder and antler-shaped—see staghorn.
| Pattern | Likely driver |
|---|---|
| Woolly mat on wood / intake | Established Cladophora holdfasts |
| Returns on the same décor | Spores left in texture |
| Soft long strings instead | Hair algae |
Likely causes (ranked)
Introduced on plants / hardscape
Cladophora hitchhikes; once anchored it is stubborn.
Quick test: New wood or plant bundle then a wool patch.
High light on slow surfaces
Rhizomes and rock stay lit while stems are sparse.
Quick test: Anubias/Java fern in the brightest zone.
Incomplete removal
Leaving holdfasts in wood grain restarts the mat.
Quick test: Same spot returns within days.
Long photoperiod
Gives leftover fragments time to re-expand.
Quick test: Lights 8h+ after a half-clean.
Fix order
-
Step 1
Physical pull — be thorough
Remove décor and scrub outside the tank when possible. Pull mats from rhizomes; trim badly coated leaves.
-
Step 2
Shorten light
6–7 hours for two weeks. Move slow plants out of the hotspot.
-
Step 3
Spot carbon on leftovers
After pulling, spot liquid carbon on remaining green in wood grain—livestock off the décor if you can.
-
Step 4
Quarantine new hardscape
Inspect new wood/plants. A quick outside scrub beats introducing another blanket.
When to escalate
- Mat fused into porous lava rock → consider replacing that piece.
- Dark antler tufts → staghorn.
- ID unsure → algae identification chart.
Helpful products
Related guides
- Hair algae — Softer filaments
- Staghorn algae — Antler shape
- Algae ID chart — Compare
- Algae hub — Parent
FAQ
Is Cladophora the same as hair algae?
Related look, tougher texture and holdfasts. Hair twirls off; Cladophora clings like wool.
Will otocinclus eat it?
Rarely enough. Manual removal is the real fix.
Can I bleach the wood?
Only outside the tank, rinse extremely well, and never with livestock in the soak water.
Does more CO₂ kill Cladophora?
Stable CO₂ helps plants compete; it won’t dissolve an established mat by itself.
How fast does it come back?
Days if holdfasts remain; weeks+ if you pulled clean and cut light.
Is “Clado” the decorative moss ball algae?
Marimo is Aegagropila, a related look but usually a ball. Don’t confuse a pest mat with a sold moss ball.
Aqua Plants Hub Editorial
