Ive had this problem quite recently. Cyano indicates your phosphates are high
To stop the cyano, I turned off the lights for about a week and it went away. I also did a couple large water changes after the cyano went away to remove those nutrients in the tank.
You have to get the cyano to go away first before the water changes or else youll be wasting water and the cyano will still be there.
In one of my new cycling tanks I put pukani rock. A few months down the road, I got a cyano outbreak. After some research I found out that pukani leeches phosphates, but I really didnt feel like taking apart the tank, so I left the rock in there and put some other dry rock in there to seed so if the leeching of phosphates didnt stop, I already had some LR and didnt have to restart the cycle. I eventually removed the pukani after my dry rock was seeded and my phospahtes are good and no cyano.