# Darkening of GDA



## Aen (Jul 24, 2007)

Has anyone had green dust turning from bright green to darker green? The ones on my rock are becoming darker but those on the glass are still bright.


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## hoppycalif (Apr 7, 2005)

GDA is unusual as an aquarium algae. It goes thru a life cycle as it grows in the aquarium. The original infestation we get is bright green and is still capable of free swimming, so when we wipe down the glass the free swimming spores just wait awhile and settle back on the glass. But, eventually it grows to a new form which is not free swimming and it eventually ends its life cycle by turning brownish in color. Shortly after that it just falls off the glass.

My many episodes of GDA convince me that we typically have several stages of the algae going at the same time, so even though the stuff turns brown and drops off the glass, there can still be younger versions growing on the glass. I am also convinced that when we have it, it is on virtually everything in the tank, but is only easily visible on the glass. I also think it grows as a green fuzz algae on plants. I have no evidence that these observations are correctly interpreted by me, but that doesn't stop me from having opinions.

What I still lack an opinion about is why it shows up - what we do wrong to make it start.


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## Aen (Jul 24, 2007)

I had Green Dust in my old 2004 tank which stayed bright green for months and even bubbled! Never witnessed any darkening.
My current tank had bright green GDA for about 3 weeks and then the ones on rocks started to darken. Easy to remove with a light scrub from a toothbrush, unlike the bright green version which I would need a razor.

I can only guess that it could be due to an accidental trace overdose, missed KNO3 doses. I'm currently running 10 hours of UV in the day so i guess that should eradicate most water-borne algae. I would need more "opinions" hah!


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