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Aquarium Algae Identification: Every Type, Cause, and How to Fix It
Last updated: May 2026
Aquarium algae identification cheatsheet bridging field observation to science-literate corrective steps—paired with calculators so livestock impact stays proportional.
| Type | Severity | Primary cause sketch | First-line fix | Biology helpers |
|---|---|---|---|---|
| Blue-green / cyanobacteria | 4/4 | Low-nitrate + stagnant flow combos | Blackout + flow reprogramming | Limited—manual dominates |
| Green water | 3–4/4 | Photon overdrive + nitrogen spurts | UV steriliser sizing | Temporary Daphnia pulses |
| Black beard (BBA) | 3/4 | CO2 choreography drift | Stabilise carbon + prudent spot dosing | True Siamese algae eater (verify ID) |
| Staghorn | 3/4 | CO2 jitter + micronutrient starvation | Prune / targeted oxidative spot | Shrimp lawns post-treatment |
| Hair algae | 2–3/4 | Photon macros vs dissolved carbon tug-of-war | Harvest + photoperiod diet | Adult Amanos, cautious flagfish |
| Green spot | 2/4 | Chronically depressed phosphate arenas | Raise PO4 deliberately + Nerites | Nerite snails (glass rims) |
| Fuzz / young-tank coatings | 2/4 | Immature biofilm choreography | Shrimps + time + CO2 mastery | Neo / cherry shrimp scouting parties |
| Diatoms (brown dust) | 1/4 | Silica residency window | Patience & scraping | Otocinclus once stable |
| Cladophora | 3/4 | Hitchhiking hardscape clones | Hardscape oxidative dip + brute removal | Limited once entrenched deep |
Decision tree (start here)
- Slimy teal sheets smelling earthy when poked? → start with blue-green remediation.
- Glass feels sandpaper-hard with polka dots wiping fails? → phosphates + Nerite strategy hub.
- Hair-thin emerald threads engulfing moss fronds? → tackle hair algae walkthrough.
- Fresh tank cocoa haze wiping clean nightly? → diatom timeline reassurance.
- Steel-wool toughness on lava rock ridges? → investigate cladophora section.
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