I had the same thing I bought these 2 colonies from a LFS and they were white I mean white and i stuck them in the tank and left them and it took around 2 months until the color came back here is one of them it was pure white and looked dead , and now this is what it looks like yes there is light at the end of the tunnel.
this is after 1 month
and this is it now its really green too and lots of PE
its actually realy green in this picture