@HSTG thank you for correcting me. That's the kind of expertise that I failed to grasp in my chemistry education. I must make a note of that. I think I'll do a search on the differences between sulfates and sulfides. I'm happy I pursued this topic now. I do have a question, though, so there was a connection between the sulfur compounds in Epsom salts being a deterrent to some types of fungi then? Also, thanks for helping me realize that copper sulfate does have a purpose.

I loved and still love chemistry but because of my initial inattention, coupled with not finding a motivational tutor, I fell behind right around chemical equations. Perhaps in the next life I'll figure it out. Thanks again. I'm going to do that search now.