You were right: that stuff is a PAIN to get into solution. Even with my trick of premixing 1/4 Tsp at a time in a Ragu bottle, I still spent the next day and a half stirring the top of the water to try to mix it in.
I've just finished the first 3-day Flub treatment and started the second stage (5-7 day) treatment. Unfortunately, the Odessa seems to be continuing to go downhill rather than improving. He still has a healthy appetite (although seems to spit food out more than the others), but he seems to still be losing weight.
Also, there's a small area on his side where he seems to be missing scales and the white-spot on his forehead is now more of a grey color and has raised edges (maybe the outer white layer of his skin at that spot fell off?). In some ways, it's reminiscent of hole-in-the-head disease, but I'm wondering if that would just be a secondary infection due to whatever this primary issue is.