gda ID

Green Dust Algae is zoo-spores and is, as the name says, green. It sits often (only?) on the aquarium glass.

 

No, it is a different variety of algae from green spot algae. Green dust algae generally covers all of the aquarium glass that is well lighted, is very soft and can be wiped off easily. Green spot algae starts as small areas of a harder algae that often has to be scraped off the glass, instead of being wiped off. Green spot algae seems to be a sign of low phosphates in the water, while green dust algae doesn't have an obvious cause.