I have had cyano bacteria in my tank queit a few times and I am pretty sure on how to exactly get rid of it.
First cyano comes from exess dissolved organic nitrogen I.e amino acids and or any kind of food that you may add starting from reef roids ending with flake or frozen. This means that you are feeding too much and cyano is the first on to come to a party and eat the easy dinner.
So reduce your feeding cut by 75% (don't worry your corals and fish will be fine! Stop any kind of Amino acid addictions and water changes.
I am assuming you are not carbon dosing if you are go algae scrubber route and or use tmc np bacto pellets ect.
Now go ahead and buy some microbacter 7 and dose the maintenance dose on the bottle do not over do it! Ask me how I know
Lastly give it around 4 to 6 weeks. Once Cyano starts receding start start upping the feeding ect by do it slowly.
PS I am no expert but this has worked for me few times in 2 different systems