Updates to comments.
Someone, somewhere said they couldn't find calgon and they settled (successfully) with Borax. That's why I chose that combo; and within the hour our daily rains commenced yet again, no evidence was left behind.
There were no witnesses, at least none that I'm aware of.
I've not seen this magic toilet wand (in my Walmart) but if this attempt is unsuccessful then I'll search one out.
Topside may/may not be sparkling, but it should smell better.
One of my favorite Lawrence Welk skits:
And I'm told NO, that's not Red Skelton (intro'd as Kenny Trimble?) ...
Now returning to regular programming, this morning I went back to top off the tank. It only held ounces before filling the actual bowl. That was cutting it close.