The Ultimate Guide to Eliminating Green Algae in Aquatic Plant Tanks

Chapter 1: Understanding Green Algae

Types of Green Algae in Aquariums

  1. Spot Algae (Chlorella)
    • Appears as hard green dots on glass/leaves
    • Common in tanks with excessive light
  2. Hair Algae (Spirogyra)
    • Forms filamentous green strands
    • Thrives in high-nitrate environments
  3. Green Water (Euglena)
    • Microscopic free-floating algae
    • Turns water pea-soup green

Root Causes

✅ Light Imbalance: >8 hours daily or intense lighting
✅ Nutrient Excess: PO₄³⁻ >1ppm or NO₃ >20ppm
✅ CO₂ Fluctuation: <20ppm encourages algae growth
✅ Poor Maintenance: Infrequent water changes

Chapter 2: Prevention Strategies

The 4-Point Defense System

  1. Light Management
    • Use timer for consistent 6-8 hour photoperiod
    • Reduce intensity to 30-50 PAR for low-tech tanks
  2. Nutrient Control
    • Maintain ideal parameters:
      • NO₃: 10-20ppm
      • PO₄: 0.5-1ppm
      • Fe: 0.1-0.5ppm
  3. Biological Competition
    • Introduce fast-growing plants:
      • Hornwort (Ceratophyllum)
      • Water Sprite (Ceratopteris)
  4. Algae Eaters
    • Amano shrimp (3-5 per 10 gallons)
    • Nerite snails (1 per 5 gallons)

Chapter 3: Removal Techniques

Mechanical Methods

ToolBest ForTechniqueToothbrushHair algaeTwirl-and-removeRazor bladeSpot algaeGlass scrapingFine netGreen waterDaily 30% water changes

Chemical Treatments

  • Hydrogen Peroxide (3% solution):
    • Dose: 1ml per gallon as spot treatment
    • Turn off filter for 15 minutes
  • Glutaraldehyde-based Products (e.g., Seachem Excel):
    • Use as directed for ongoing prevention

Blackout Method

  1. Cover tank completely for 72 hours
  2. No feeding during treatment
  3. 50% water change afterward

Chapter 4: Long-Term Maintenance

Monitoring Schedule

  • Weekly: Test NO₃/PO₄ levels
  • Biweekly: Clean filter media
  • Monthly: Trim plants & scrape glass

Advanced Tactics

  • Implement CO₂ injection (20-30ppm)
  • Use UV sterilizer for green water
  • Dose competitive bacteria (e.g., Microbe-Lift Special Blend)

Troubleshooting FAQ

❓ "Algae returns after treatment?" → Check phosphate sources (overfeeding, tap water)
❓ "Safe for shrimp?" → Avoid copper-based algaecides
❓ "Best natural solution?" → Floating plants + reduced lighting