Sound like you might have Filamentous Algae

From Aquaplant:

Filamentous algae are single algae cells that form long visible chains, threads, or filaments. These filaments intertwine forming a mat that resembles wet wool. Filamentous algae starts growing along the bottom in shallow water or attached to structures in the water (like rocks or other aquatic plants). Often filamentous algae floats to the surface forming large mats, which are commonly referred to as "Pond scums." There are many species of filamentous algae and often more than one species will be present at the same time in the pond.


Does this look familiar?


Or this?



JHAP
~~~~~~~~~~

"My mind is a raging torrent, flooded with rivulets of thought cascading into a waterfall of creative alternatives."
...Hedley Lamarr (that's Hedley not Hedy)