Purple scoreline growth in 1 week?

[Ryane7]

Hi new two the board I haven't had a reef tank in about 15 years just getting back into with my son. Anyway I've setup a 55 gal with 40 lbs dry rock only been in the water for 5 days. it's currently under an old t5 lighting but will be changing to Led's (back ordered). diatom began to bloom today but I also found a purple growth near the top of the tank is this coreline algae.

 

[Flippers4pups]

Yep looks like you have coraline starting!

 

[Ryane7]

That's what it looked like but just surprised to see it so soon rock was put in tank 4 or 5 days ago