Cyano can be part of the natural cycle of competing organisms in a tank's life. Or it can be the symptom of a nutrient imbalance, or old bulbs, or low flow.. lots of things can cause it.
While products like chemi-clean and red slime remover will kill the cyano, they don't address the core problem, whatever it is.
If you have cyano smothering corals, a chemical product may save the corals, but if at all possible, consider siphoning out the cyano as you work on figuring out what the true problem is (if one exists at all.)