Black patches on acros after a dip

[Stick-y]

Hi,

I dip regularly all my corals in my frag tank with some kind of CoralRx. This morning, after the dip, I noticed these black patches on several acros. Everything else is fine, parameters are on top.

There wasn't any visible pests in the dipping container after the bath. Has anyone already encountered something like this ?

Thanks !

 

[Gumbies R Us]

Did the patches ever go away?

 

[Stick-y]

Did the patches ever go away?

Well, the patches are slowly disappearing. I didn't do anything