Iv had the problem literally for months and finally just got it to go away. It was definitely a battle but try to kill it while its in an early stage. I cut way back on feeding, did water changes twice a week, heavy skimming, constantly cleaned my carbon filter, sucked it out, added purigen pack (to remove some phosphates), and I hate to say it but I gave in and finished the rest off with 2 doses of chemiclean. Now I am not at all a promoter of adding antibiotics to the tank but to finish off that last tiny bit of cyano
after all the hard work was worth it. I do however feel that the product is just a bandaid that only temporarily covers the problem. Also, I changed my old bulbs to LED
lighting. I have heard old lights can promote the bacterial growth. I have no clue how reliable that info was but if I heard it worked I tried it and its finally gone so I must have done something right. The biggest thing is to know where you stand with all your parameters and to keep those in check. Dropping temperature a little and less lighting may also be an option that could help. The process was not fun but well worth the work goodluck hope this helped just a little!