My lfs gave me a big bottle because they said it didn't work. I used it and have it all over my rock. I used it when the tank was 3 months old. I started with dry rock
Tank about 2-3 months old
Taken 2-3 weeks ago. You can see it on the rock. It progressed this much shortly after using purple up and hasn't seemed to spread much since.
I used to use it. Yet I dont like scraping the coraline off the front and side of my tank. If the goal is to keep your calcium, mag, and akl stable use BRS's 2 or 3 part system.