Why isn't my coraline algae growing!

[Timbits]

Originally Posted by jtbadco

IME it tends to catch on quicker if you add pieces of LR that already have coraline on it.

I also used a product called Purple Up to encourage growth. I believe it adds other elements that are necessary or helpful in growing coraline. It worked in my first tank.

I've heard of this product... how effective is it?