Can Potassium Metabisulphite be pre-mixed in distilled water? - Home Brew Forums

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Old 05-02-2011, 02:28 PM   #1
May 2010
Wixom, Michigan
Posts: 609
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I don't have a scale that will measure in 10ths of a gram. Since I can't weigh out 1/2 have gram (500 mg), which is the recommended amount to treat 20 gallons of water to remove chloramine, I'm thinking of weighing out a full gram and adding it to 2 oz of distilled water. When I need to treat 20 gallons of water I'll pour 1 oz of my pre-mixed solution into it. Will this work?
Vir sapit qui pauca loquitur

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Old 05-02-2011, 03:41 PM   #2
Aug 2010
McLean/Ogden, Virginia/Quebec
Posts: 9,195
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Yes, you can but I don't think the solutions are stable so you would need to mix just before use. This is definitely recommended for Campden tablets which are a bit difficult to dissolve.

The amount of bisulfite used does not have to be dosed in exactly. If you can weigh out a gram you could easily estimate visually how much powder it takes to make up half a gram. You could also weigh out a gram, divide the powder into 4 equal portions, add the first portion and then check for chlorine smell. If there is no chlorine smell you've used enough. Note that the 1 tablet (~500 mg) dose is based on 3 mg/L chlorine equivalent and most suppliers don't use that much so that less than 1 tablet will often do. The reaction is fast and once the chlorine odor is gone you have added enough. Obviously if the chlorine odor persists you can add another quarter (or maybe half of a quarter) and check again. If you overshoot and add to much there is still no problem as metabite is harmless to beer (and people with the exception of those who are allergic to it).

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Old 05-02-2011, 03:52 PM   #3
Dr. Francois
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Jan 2009
Okemos, MI, Michigan
Posts: 614
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Excellent idea!

I'm getting tired of making tiny little piles of white powder with a razor blade on my glass-top kitchen scale...makes the wife nervous.

I mostly use the chemical in my seltzer keg. I didn't one time and it was like drinking a carbonated swimming pool.
Dr. François

"We are what we pretend to be, so we must be careful about what we pretend to be."
--Kurt Vonnegut

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