Thanks I might do the chemi clean for last resort.Man i really feel for you. I don;t have any solutions, just sympathy...
When I had Cyano the owner of the LFS told me to make sure I killed it all with the first treatment of chemi clean or it may build up resistance and become super cyano. I ran it 24 hours and that got rid of 95% of it. So instead of doing the water change and a second dose, I let it go for an additional 12 hours, and it has never come back. My system is very small though. 32 gallons.