What temp does it (cold water filamentous algae) die off at?
Most can guess my first response - "It all depends". It depends primarily on the species of algae. Individual species can have specific temperature preferences. I am talking species of algae here not genera as in a scientific name of Genus species. The Genus grouping can have numerous species within it similar to the genus Lepomis (panfish sunfishes). Another example would be threadfin, and gizzard shad. Both in genus Dorosoma, but one preferring warmer temps. Within a genus one can be warm loving, one cold loving and several with no temperature preference technically referred to as eurythermal - tolerating a wide temperature range.
The big problem with all this is to get a specific name for many of the species of at least green algae, one has to see them in certain reproductive stages which is not all that common so they can then only be identified to genus.
