coraline is calcarious (hard) comes in many shades of purple of course being the common color but I have bright red, red, cream, beige, and green coralines. Cyano also comes in many colors (cyan means "blue/green") but red, brown and almost black are common. And as dragon said it can't grow in flow. Reach in and touch it - if its soft siphon it out with a hose without the gravel attachment on. It should subside in your tank unless you have a serious issue of flow, nutrients (well all water parameters), or lighting. And I would not recomend any of those products - I know some people have success with them but I have a freind who tried it and it caused her corals to bleach, not worth the risk to me, proper maintenence is a better solution.