As far as reading the meter, you're correct - no decimal point. If it reads "044", then that's 44 ppm
From your earlier post with the TDS
readings at different stages, it definitely sounds like something is being picked up by the water from your barrel. One thing that concerns me is that you said it's "food grade", but you picked it up at a feed store. Is it truly FDA "food grade", meaning approved for contact with human food? Or is it just "good enough" for use around animal feed?
Reason I ask is that in the past, I read somewhere on a forum (not here) about someone using a feeding trough to store water. Long story short, something leached into the water from the trough that killed a bunch of livestock. The general consensus was that whatever was used as a mold release in the manufacture of the plastic trough, tainted the water.
If you cleaned it with bleach and soaked it with dechlorinator, I don't know of any better way to clean it. It's going to be more thorough than a vinegar bath. But I'd be concerned if it still has some type of odor even after the bleach bath.