Yes, if you're getting a lot of cyano when dosing vodka, cut your dosage back in half and begin the progression again from there. Also perform all of the maintenance needed to rid yourself of cyano, water changes, siphoning, aggressive skimming, increased mechanical filter maintenance, reduction in feeding and lastly although I am not a big proponent, decreased lighting schedule.
Also how is your skimmer performing? You must have a good skimmer to remove the bacteria that is dying on a regular basis. If not the fuel for the cyano is just being accumulated and reintroduced to the system.
Also cyano, being a bacteria, also uses the carbon as a source.
What is your water source and could you be introducing phosphates in excess of what can be handled?(or perhaps food source introducing phosphates?)