Originally Posted by richyang http:///forum/post/2918156
The red stuff start to grow on my rocks and i dont know is it good or bad
Are those bubbles on that? I am bad at this unless it's in person. Can you easily blow it off the rock? It looks like some DARK coralline...If it is almost part of the rock, then it is coralline. If it has bubbles and is easily blown off the rock, then you have something bad, probably cyano.
That is cyano alage, Caused by excess nutrients in your water fueling it's growth.
How often do you feed?
What kind of flow and how much flow do you have?