Cyano :(

[Northvan]

We feel your pain. We've been fighting it for a year. We've done chemiclean (temporey improvement, but comes back), 3 days lights out with tank wrapped (no improvement at all), just finished a bottle of cyano clean with coral snow (1 month, $120, actually seems to have gotten worse).
We haven't yet tried erythromycin (antibacterial), not sure how to dose it.
Tank is almost no fun anymore.
Cyano sucketh .