Originally Posted by DirtySubstrate
I also noticed that on the base of a couple of my larger rocks it appears that it is turning a very bright lime green color. Is this an algae?
This can possibly be coraline algae which comes in many different colors like purple, orange, rust, green, maroon, etc.
Might be another diatom bloom that you are having. The major algae to worry about is cyano
and hair algae.