Green Goo

[Lansirill]

I have some green goo growing on my hornwort. I'm guessing it's some type of algae, but I really don't know. I pulled out as much as I could find, but I imagine it will come back. It seems to grow as a film, and will make a webbing (for lack of a better word) between needles on the hornwort. Any ideas what this stuff is?

 

[msjinkzd]

http://www.plantgeek.net/article_viewer.php?id=9 is a good algae guide. Sounds like it might be cyanobacteria (blue-green algae). It is caused, I believe, by low nitrates. You can manually remove it (it will come back) or you can treat with erythromyacin. If you use the antibiotic, watch your biofilter as it can cause it to crash. You may need to start dosing nitrates (if you aren't already) to help prevent future outbreaks.