Zoa colony dying?

[MNscoe]

I’m a relative beginner, tank is one year old. I added a Zoa colony of about 10 heads which grew nicely for a few months into about 20 heads. Happiness!
Then it just started not thriving. It appears to be covered in mold or spider webs, and heads are dying. See pic. That little square frame was invisible under flourishing heads before. Now almost all dead it seems.
My tank parameters are stable and good except high phosphates (0.1 ~ 0.3).
Any ideas what is wrong?

 

[Tahoe61]

A sponge is over taking the Zoanthid. Take a soft tooth brush and remove sponge. Ideally in a separate container, or siphon out. A hydrogen peroxid dilution dip wouldn't hurt.

 

[littlebigreef]

@Tahoe61 for the win.

Doesn’t look like a bacterial/protozan pathogen. A 1:3 h2O2 to tank water for 5-7 mins and then a gentle brushing with a soft bristle tooth brush should set this right. If you happen to have lugols an additional 5-7!mins in a bath with 20oz tank water + 6-7 drops will certainly help.

 

[MNscoe]

Thanks folks!
This Zoa colony was glued to the rocks so I can’t dip it. So I will try gentle brushing and siphon….

 

[MNscoe]

Hi folks, after doing a gentle scrub and siphon and then in-situ Lugol “wash” it didn’t help. The colony is now definitely dead. Today I realized there’s a greenish “mold” growing in that area, and got a good picture of it on my rocks. I’m pretty sure this started on the Zoa colony (just at top of this pic) and killed it, and is now spreading slowly.

Any idea what it is, and what to do about it?