Bob Engelhardt wrote:

I didn't take the valve off, so I didn't pour in much - maybe a cup.
Sloshed it around a bit and let it sit overnight (I suspect that the
sitting overnight wasn't necessary). Poured it out (and rinsed?). Did
not fill with water.

I tried the bleach last night. I did have the valve off, so it was easy
to pour in 1-2 cups and then fill the tank with hot water. When it was
half full I plugged it and picked it up and sloshed it as violently as
I could. Then I removed the plug and filled it the rest of the way with
hot water. It foamed orange out the top. This morning I poured out the
solution. It was all orange, like slightly diluted orange pop. No smell
anything like the mercaptan. Nor did the orange look like rust, although
it may have been, bleach I believe being an oxidizer. At any rate it
wasn't enough to worry about. It looks like the bleach works. When it
gets light out I'll blow the tank out with an air pipe and then let it
dry in a warm place until I'm ready to cut it open.

I now feel like I've dialed in the process. I might even shoot a photo
of how I clamped the tank to remove the valve, it worked real well.

Grant