Awesome. That is a very informative and great reply. And yes I'm currently treating with salt too . Ok yea I'm putting my carbon back in to take remove the tetra guard out today. Thanks.
I think a lot of people(maybe not in this case) misidentify black spot for natural pigments/freckling found in some ornamental lines. Only way to know for sure is to microscopically identify.
There is an old thread on here somewhere, where one of the mods had some freshly imported WC geos with black spot disease. I gave the same advice back then, as I did here. He had posted some pics I believe, I'll see if I can find it.