This article is from the Aquaria: Disease, Algae and Snails FAQ, by Elaine Thompson, Thomas Sasala and George Booth
Grows in long, thin strands up to 30 cm or more. Tends toward a dull
green color (hard to tell because it is so thin). Usually indicates an
excess of iron (> 0.15 ppm). Easily removed with a toothbrush like
hair algae.
 
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