I would start with the new light being on for 2 hours a day, 7 days later bump it up to 3, 7 days later bump it up to 4.....etc.
You can siphon the cyano off when you do water changes. If you have urchins they usually eat it. Chemical additives can be used but extremely cautiously when corals are present, especially sps. If you've never had it before, than I'd think reducing the photo period would be a good start and then siphon what you can off.