Green Algae
Green Spot Algae
Coleochaete family (commonly associated)
Hard green dots that cling strongly to glass, rocks, equipment, and slow-growing leaves.
Quick facts
- Category
- Green Algae
- Organism group
- Green Algae
- Growth form
- Spot
- Primary color
- Dark Green
- Secondary color
- Green
- Attachment
- Strong
- Removal difficulty
- Moderate
Identification
Small, flat, round green spots that can expand into hard crust-like patches if left alone.
- Growth form: Spot
- Primary color: Dark Green
- Secondary color: Green
Looks like: Unlike green dust algae, these start as stubborn individual dots and are usually hard to wipe away.
Where it appears
Typical affected areas
- On Glass
- On Plants
- On Hardscape
Common contexts
- Too Much Light
- Nutrient Imbalance
Causes
Frequently appears in brightly lit tanks, especially on hard leaves and front glass.
Most common triggers
- Strong Light
- Phosphate Limitation Is Commonly Linked
- General Plant Growth Imbalance
Root cause note: GSA often shows up when light pressure is high relative to nutrient availability and plant uptake.
Nutrient relevance
Balance relevance: High
Related nutrient issues
- Low Phosphate
- Carbon Dioxide Or Growth Limitation
A persistent increase in spot algae is often linked in the hobby to phosphate-related imbalance.
Correction hint: Tighten nutrient consistency, especially phosphate availability, before changing multiple variables at once.
Treatment
Quick action: Use a blade scraper on glass and trim badly affected hard leaves if needed.
Mechanical removal plus better nutrient balance and a sensible photoperiod usually works best.
Manual removal: A blade works best on glass; old Anubias-type leaves are often easier to prune than to clean.
Difficulty: Moderate
Prevention
Avoid excessive light duration and keep plant growth strong with stable nutrients.
This page is designed to help with visual identification first, then causes, treatment, and prevention. Actual algae pressure can vary depending on maintenance, livestock, plant mass, light, flow, and nutrient consistency.