I agree with the comments above and to clarify, this means that we start
seeing small pink and/or purple spots only. It can take a year or more
for those spots to grow to the size where they begin to connect
together.
At this early stage I treat the spots as if they were gold. If at all
possible I do not scrape them off the glass because those small growths
are now helping seed the entire tank.
Below is a nice pic of some LBTR which clearly demonstrates the beginning
stages of coralline growth. Good LBTR does not have this solid flat
surface, but this piece was such a good example of new Coralline growth, I take the chance
and will refute the criticism if it comes.
Note that green Coralline Algae populates the surface very fast and only now
at about 4 weeks can tiny pink dots be seen. Don't be discouraged if yours doesn't look like this. This was in a well seeded tank with
conditions ideal for Coralline growth. If you would like to learn more about those ideal conditions, please feel free to call and come visit with me in Murray.