Help determining algae source

[mrcoffee2]

Randy,

What is causing this to grow on some of my rocks? It has me baffled!

 

[Reefing Madness]

Water parameters?

 

[JMSKI333]

How old is the tank? How old is the rock? Where did you get it? My first guess is that your rocks could be leaching phosphates, but I am not sure. We will need some more info.

 

[Randy Holmes-Farley Verified Community Expert]

Is it on all of the rocks, or just a few?

Do you have any herbivores?