I have a 260 that has been set up now for over a month now. I noticed this week that i have a rock that is covered in purple agae kind of like coraline algae, BUT THIS IS A FRESHWATER TANK. soo i was wondering what this could be.
Most likely some sort of cyanobacteria. There's also a freshwater red alga called Hildenbrandia that forms crusts on rocks, very similar to its marine cousins.
