Zinc usage - amount for healthy fermentation

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In small letters on the label "Not for food or drug use."
Good looking out. It is reagent grade, which speaks to it's purity at least. Better than nothing. A label that says "not for food use" typically just means it hasn't been tested for that purpose. Realistically, as long as the purity is on point with this, it should be moot, since the amount used is SO miniscule.
 
This is the best liquid option I've found. Gotta make sure the only ingredients are zinc sulfate (in whatever form) and water.

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Maybe just wave the open bottle over the fermentor?
Pretty much. Here we go:

Per the label, 10 drops = 15 mg elemental Zn, so 1 drop = 1.5 mg
If you're dosing 5.5 gal of wort, that's 20.8 L, so
1 drop in 5.5 gal wort => 1.5 mg in 20.8 L = 0.07 ppm (mg/L)

The general concensus is that you need to achieve 0.3 ppm elemental Zn for ales, 0.2 ppm for lagers, but considering 0.1 ppm carries over from the mash/boil, you need to dose 0.1 to 0.2 ppm. That's the equivalent of 1.4 to 2.9 drops of the 30,000 ppm solution per 5.5 gal wort.

You might get away with it, but obviously measuring by drop is inherrantly inaccurate. Not a risk I'd be willing to take, as overdosing can be toxic to yeast and have the opposite effects of what you're going for.
 
You might get away with it, but obviously measuring by drop is inherrantly inaccurate. Not a risk I'd be willing to take, as overdosing can be toxic to yeast and have the opposite effects of what you're going for.

Probably better to pipette 1ml into a container and dilute with distilled water up to, say 100ml. Then adjust your addition by a factor of 100. You can deal with ml instead of drops.
 
https://alphachemicals.com/zinc_sulfate

Marked as "feed grade" for animals.
That doesn't automatically make it unsuitable for brewing, especially in the light of the infinitesimal (very small) amounts used for our purposes: micrograms in a 5 gallon batch. But let's not debate food grade vs. feed grade vs. lab grade vs. reagent grade vs. pharmaceutical grade vs. whatever-other grade.

I'm not endorsing using non-food grade chemicals, nutrients, and other products for human consumption, even in whatever small quantities they may typically be ingested.

Good looking out. It is reagent grade, which speaks to it's purity at least.
Exactly!
For those interested, here's a site that describes various "grades:"
https://goldbio.com/articles/articl...ratory#:~:text=Reagent Grade– A high purity,4.

Heer's one of the threads discussing the use of Zinc in brewing:
https://www.homebrewtalk.com/thread...d-water-mashed-beer-leads-to-harshness.653771

In that thread, @Silver_Is_Money mentions using Good State - Ionic Liquid Zinc Ultra Concentrate drops (Post #9) the same drops @MaxStout linked to, above (in post #35).
 
Ok, so if I have this right:

1 ML of the zinc solution contains 30mg of zinc
If I dilute 1 ML of it in 100ML of DI water each ML now contains 0.3 of Zinc.
A 5.5g batch could use up to an additional 4.35 mg.
So I would add 14.5 ML of the diluted solution per 5.5 gallons of wort.

Look right?

Cheers!
 
FWIW, measuring in drops can be perfectly adequate if consistently applied and calibrated (ideally with the actual liquid being measured). We don't need 1% precision!

IMO I'd rather not store 1:100 diluted solution for extended periods. Too much chance for spoilage, and who knows what the original relies on to maintain suspension.
 
IMO I'd rather not store 1:100 diluted solution for extended periods. Too much chance for spoilage, and who knows what the original relies on to maintain suspension.
Measuring in drops can be precise, but less likely to be accurate. My point being that on our homebrew level, we're not likely calbrating equipment to be accurate and precise at the drop-level.

Also, I was then going to mention: it's suggested to prepare the stock solution with boiled water, sanitize the container (pros often autoclave their equipemnt for this), and acidify the solution to keep the Zn dissolved.

From White Lab's Yeast Buddy product page:

IS THE SOLUTION PH IMPORTANT?

Yes! The low pH (4.0) helps the zinc salt remain soluble in solution, providing the most optimal delivery to yeast cells. If zinc isn’t soluble, it can’t efficiently be taken up by yeast.
 
I started writing a procedure for calibrating a dropper (which is very easy), but then realized this thing comes with a calibrated dropper, lol. No need to make it more complicated than 1 drop = 1.5mg, if you trust whatever factory made that stuff. No USP stamp.
 
What about just adding a hot-dip galvanized washer or spike, or a post-1982 penny with all the copper sanded or etched off, to the kettle or to the fermenter? Won't traces of zinc leach into the wort? (if most of it from the kettle gets bound in the trub, that might be a good thing so you don't overdose it) I believe German breweries in particular, perhaps unknowingly, used to get their zinc from galvanized and brass fittings.
 
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