What to treat zoanthid fungus with?

[Aikachinatsu]

my zoa frag has some white fungus growing on it and all of the polyps are closed.
parameters
ammonia 0
nitrite 0
nitrate 0
ph 8.4
salinity 1.025

I've heard some good and bad things about using furan-2, and also Lugol's iodine. Any help is appreciated

[Aikachinatsu]

Here is a picture of the sick zoa

[cloak]

I think Hydrogen Peroxide will work as well. The ratio of peroxide to water is like 1/3 if I'm not mistaken.

[Aikachinatsu]

I can try that. The white fungus covered polyps in the picture have now completely disintegrated within the hour! Now it's like it is just a little skin with black powder... The other polyps don't look infected but they are closed.. What could cause this?!