Algae fix guide
Green Dust Algae
Also called GDA
A fine green haze on the glass that wipes off, then comes back within days.
By Mike Elmira
TL;DR, Green Dust Algae
Green dust algae is the fine green film that coats the glass and returns almost as soon as you clean it. The trick most people get wrong is wiping it too early. It has a life cycle, so if you leave it alone for around three to four weeks it matures, releases spores and sloughs off on its own. Do one big wipe and water change at that point rather than scrubbing every few days, and it usually breaks the cycle for good.
How to spot it
A soft, even green dust or haze across the glass, often worst on the brightest pane. It smears rather than scrapes, and it grows back fast after cleaning.
What causes it
- A young tank finding its balance
- Cleaning too often, which resets the algae's life cycle and keeps it coming
- Bright light on bare glass
How to fix it
- Leave the glass alone for three to four weeks and let the algae complete its cycle.
- Once it starts sloughing off in sheets, wipe the whole pane and do a large water change the same day.
- Clean the filter and vacuum any loose debris so the spores go with the water.
- If it returns, repeat the full cycle rather than wiping little and often.
Keep it from coming back
Resist the urge to wipe every couple of days on a new tank. Let the tank mature, keep dosing steady, and it tends to sort itself out.
What eats it
Nothing really eats green dust algae. It is about riding out its life cycle, not adding a clean-up crew.
Frequently asked questions
Direct answers to the questions search engines and AI assistants surface most often about this species.
Should I wipe green dust algae off or leave it?
Leave it for about three to four weeks, then do one big wipe and water change once it matures and starts falling off. Wiping every few days just keeps the cycle going.
How is green dust algae different from green spot algae?
Green dust is a soft haze that smears off and regrows fast. Green spot is hard little dots you have to scrape. They have different causes and different fixes, so it is worth telling them apart.