Coraline Algae

+1 with everything above.. just keep the levels in check and you dont even need the greatest lighting cause mine is horrible and my corraline is growing like wildfire.

 

The reason I asked about the white thing is that I put in some live rock into my two week old tank that had green coralline all over it and now it is turning white which means it is dying right? But on some of my other rocks I see the white growing on them and some of it is starting to turn to the green color, to the touch it is hard though like coralline.

 

Yes that is dying coraline, and the green is new coraline. It usually grows better on the white areas first--then later will turn purple. At least that is what I experienced.

 

The green is more likely regular algae just growing on top of the dead coraline.

It is quit common for coraline to die off. If you put a rock low in your tank, the coraline that likes bright light will die off. The low light loving coraline will eventually take its place. Same is true if you put a rock high in your tank. If it is loaded with low light loving coraline that will die off. Eventually it will begin growing high light loving coraline.

 

just seen this thread again - thanks for the kind words folks