"i have that my tank is about a week old? should I do anything about it?"
It may go away on its own. Reduce feeding. Watch phosphates ..... basically everything everyone else has said.
However, I have had really good results with chemi-clean. If you are like me and do not or cannot afford a do/ri unit , it can give you the upper hand. It is an oxidizer that is added directly to the tank and helps to clean up the cyano
. It doesn't seem to harm the critters when you follow the directions. Once I was able to get on top of the problem, it has not returned.