Calcualting free so2 requirements.."More Wine" contradiction?

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Siwash

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Hey folks,

So my wines require So2 additions. The problem is More Wines contradicts itself (It think). On pages 64-65 of their PDF file, there is a chart that states that a wine with a PH of 3.5 requires 40 PPM of "free" SO2. but on the next page, it gives another number - 24PPM.

How much "free" S02 is required for a wine with 3.5 PH? My free SO2 is currently at 10, 12 and 8 for the three demis I tested... each is between 3.5 and 3.54 PH

So do I subtract 40 PPM from 12 PPM (and 40-8 and 40-10 for the other two?), which in this case, would give me 28 PPM to plug into their equation?

I am confused! Why do they have two different figures? Is this a typo?

thanks
 

ibglowin

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There is usually a level for red wines which is the lower number and then a level for white wines which is the higher dose rate. Red's do not need as much protection at the same pH level due to tannins etc which are antioxidents. You can use the higher dose rate for reds if you want. Won't hurt your wine in the least.
 

Johnd

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Hey folks,

So my wines require So2 additions. The problem is More Wines contradicts itself (It think). On pages 64-65 of their PDF file, there is a chart that states that a wine with a PH of 3.5 requires 40 PPM of "free" SO2. but on the next page, it gives another number - 24PPM.

How much "free" S02 is required for a wine with 3.5 PH? My free SO2 is currently at 10, 12 and 8 for the three demis I tested... each is between 3.5 and 3.54 PH

So do I subtract 40 PPM from 12 PPM (and 40-8 and 40-10 for the other two?), which in this case, would give me 28 PPM to plug into their equation?

I am confused! Why do they have two different figures? Is this a typo?

thanks
In the Morewine SO2 Management Protocol manual, the following chart link:

http://morewinemaking.com/public/pdf/so2.pdf

shows 40 ppm as the target value for a wine with pH of 3.5.

Using Fermcalc (which I always do), targeting 40 ppm, with initial ppm of 10, wine volume of 12 gallons, pH of 3.5, the addition of 2.3645 grams of sulfite powder is required to bring your wine up to 40 ppm free so2. I'd suggest that you use fermcalc for each of your demis (although they are nearly identical anyway) and make the adjustments as calculated. It's always put me pretty much on the mark........................
 

mfzona

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This calc will tell you what you need to add as well as what the desired free target is based on pH.

https://winemakermag.com/1301-sulfite-calculator

I suspect the two different numbers you see are based on the desired MOLECULAR SO2 level. Most use 0.8 mg/l as the standard molecular level (in your case yielding 40ppm at 3.5 pH. SO2 can be effective at 0.5 mg/l and would yield 25ppm at 3.5 pH for some that try to minimize the amount of sulphite they add. Riskier in my opinion.
 

salcoco

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why not ask them, More Wine, in a email rather than all of us guessing. they are pretty responsive.
 

Johnd

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I found the two references you cited in your original post. The chart shows 40 PPM for wine pH of 3.5, this is the same as any other chart I've ever seen showing recommendations for free so2 based on pH, and I believe it to be the correct number. I've no clue where the 24 comes from on the second page, 40 is the number I would, and do, use for 3.5 pH.
 

ibglowin

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I am telling you recommended dosage for white is 0.8ppm and red is 0.5ppm as I mentioned in my post above.

You can find references citing this all over the place. including this one from PI Wine.

"0.8 mg/l of molecular SO2 is considered the needed amount for white wine and 0.5 mg/l for red wine.

http://www.piwine.com/media/home-wine-making-basics/using_sulfur_dioxide.pdf

Do the math. 0.5/0.8 = 0.62

24/40 = 0.60



I've no clue where the 24 comes from on the second page, 40 is the number I would, and do, use for 3.5 pH.
 

Siwash

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thanks guys... I went with the 40 PPM for 3.5 and adjusted accordingly for the wines measured at 3.6..

I thought it was 40 but that other figure threw me off
 

Johnd

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I am telling you recommended dosage for white is 0.8ppm and red is 0.5ppm as I mentioned in my post above.

You can find references citing this all over the place. including this one from PI Wine.

"0.8 mg/l of molecular SO2 is considered the needed amount for white wine and 0.5 mg/l for red wine.

http://www.piwine.com/media/home-wine-making-basics/using_sulfur_dioxide.pdf

Do the math. 0.5/0.8 = 0.62

24/40 = 0.60
Respectfully Mike, I fully recognize the difference between .5 and .8 molecular SO2. As I said, I would, and do use 40 from the .8 graph. The math, if done correctly, yields 25, not 24. 40 * .5/.8 = 25, which is why I cannot explain the the OP where 24 came from. My opinion, which I still hold, is to use 40.
 

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