If left to its own devices, cyano can quickly get out of control and begin to grow on corals. The sooner you get rid of it, the healthier your tank will be. I would get tons of macro (assorted types), and immediately follow up with an RODI water change. Then I would remove any carbon that you might be running, and use either Chemi clean or Poly Ox (as directed). I would gently remove any excess cyano daily, until the macro have the nutrients under control. Just be vigilant. And make sure you have good flow in all areas of the tank - detritus and other organic matter will help fuel cyano growth. Good luck.