I'm sure there is some science behind it's propagation. As I said, it is also interesting it grows on power heads. I have some power heads that were in use for years that are just a clump of Coraline algae.
I think everyone agrees that good water quality and plenty of calcium is a good start. My LFS
cultures live rock and grows Coraline algae on artificial reef rock in a tank on his bottom shelves. Very low light levels and rocks get covered in a few months time. The Purple Up works as well if all the rest of the conditions are there.