I have been running my tank for about 1.5 years and I'm barely starting to see the coralline I yearned for since I started. I only started using purple up some 2 months ago. What a coincidence that my coralline growth surged and the coloration on it is phenomenal just after using it. Ca: 450-500ppm steady, dose all necessary elements including Str for my Acroporidae and my Alk being at a solid 10dKH; all for 1 year with ZERO results. Coralline never died, but spread EXTREMELY slow and no intense coloration noticeable. I've never had such "rich" coloration in my existing coralline. As a matter of fact, check out my acan pictures in the classifieds section and look at the photos, look how lush it looks! inwall: I would rather have coralline growing everywhere than hair algae! hehe. But yes, it isn't scrape friendly! Also, as inwall mentioned Str is essential for the skeletal development of stonies. It's the first thing utilized to develop new skeleton followed by Ca as a re-inforcement. It's also amongst the chemicals that are used up FAST! So dose it!