Algae – Green Dust & Fuzz

February 28th, 2008

At the last GWAPA meeting, I gave a presentation called Algae in the Planted Aquarium. While preparing for the presentation, I had to gather a lot of information from a number of different sources on the Internet. I’ve decided to declare this week Algae Week, and share that gathered information by posting about two types of algae each day. This is the fourth installment featuring Green Dust & Fuzz Algae.

Green Dust Algae (GDA)

Green Dust Algae (GDA)

Green Dust Algae (GDA) is a “dusty” green film that appears on the surface of the glass. It’s caused by zoo-spores, and seems to avoid attaching to hardscape items or plant leaves.


  • Unfortunately, I haven’t been able to locate a concrete cause for GDA.


  • Leave alone – GDA appears to have a finite lifecycle, so that if you allow it to run full cycle without scraping it from the glass, it should harden, and fall off after roughly 21 days. After this time, scrap any remaining GDA from the glass, and do a thorough cleaning and water change.
  • Nerite Snails – Nerite snails can help eat through some of the GDA on the glass, but the approach above will likely have to be undergone for full removal.

Fuzz Algae

Fuzz Algae

Fuzz algae often shows up on plant leaves giving their edges a slightly fuzzy appearance.


  • Nutrient Imbalance – Strive for the following nutrient levels: N (10-20ppm), P (0.5-2ppm), K (10-20ppm), Ca (10-30ppm), Mg (2-5ppm), Fe (.1ppm).
  • Low CO2 – Strive for 20-30ppm concentration of CO2, as permitted by fauna.


  • Maintain proper nutrient/CO2 levels
  • Algae Crew – Siamese Algae Eaters (SAE), Amano shrimp, Otocinclus, and Mollys are known to eat this algae.


Aquatic Plant Central Thread
Aquatic Plant Central – Algae Finder

6 Responses to “Algae – Green Dust & Fuzz”

  1. Rami Says:

    GDA has occured in the past in my tanks when excess feedings occurred, and under the strongest light. It doesn’t like my flourescent lights, but my regular lightbulb used to cultivate it crazily. A new, clean toothbrush scrubbing and careful food monitoring solves my GDA problems. 🙂

  2. guitarfish Says:

    Thanks for your experience Rami. Excess feedings can trigger all kinds of algae troubles. I’m glad you got yours cleared up!

  3. Rami Says:

    You’re welcome. GDA and that brown algae is all I’ve ever had to deal with, thankfully. Mild, and moderately easy to get rid of.

  4. Naja002 Says:

    Rami, it sounds like GSA (Green Spot Algae), not GDA. GDA wipes right off–so, there’s no need for a toothbrush scrubbing. GSA does not come off easily–that’s where a toothbrush would come in. HTH

  5. Rami Says:

    Naja002, it is GDA. It wipes right off, I just use a toothbrush for removal.

  6. Green fuzz algae Says:

    […]…reen-dust-fuzz It looks like small short stands of hair algae that forms a carpet. it looks soft, like green peach fuzz. I have been dosing to maintain proper balance now, but can seem to get rid of the rest that has taken over my tank. Does this algae have a natural life cycle where it dies off? […]

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