cyano in a new tank is common - let it run its course and the last thing you want to do at this point is start dumping meds in. best case scenario that may kill the cyano but it may kill other bacteria as well and all that death will just fuel no3 and phosphates. let the tank age - change water, siphone, keep it as clean as possible, and be patient it will go away. also as sadie said look at flow and overfeeding issues. JMO