why????

[goober]

why is my live rock turnig white? i have 10 snails and 2 clowns with 1 domino damsal my tank just finished cycling

 

[broomer5]

I've had the same thing happen to a few pieces of my live rock when first introduced. It's not uncommon at all to have some of the pink & purple coralline algae turn white. It will grow again on the white areas if your tank water conditions are good - alkalinity and calcium levels maintained, and decent lighting.
Sort of a bummer - but nothing to get too worried about.