Binox worked on mine. About 90% cleared up in 3 days, did water change and didn't
treat again. The rest cleared up on its own. Maybe it isn't fungal.
As for as sulfa, Ross states that when you don't have access to injectable antibiotics,
nitrofurazone is the most useful. Don't know how updated this is
since his books were published. Absorbtion and Bio Filtration being
the main reasons I assume.
Especially since it only effects gram negative fungus.
Like Nic stated Maracyn/Maracyn II would cover both positive and negative.