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Memorial Day Sale - Today Only! - 20% off Wine Kits! LIMITED SUPPLIES

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Old 03-20-2017, 10:50 AM   #1
Kraffty
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My new SO2 testing kit arrived last Friday. List price everywhere is $299.00 but Midwestsupplies.com sent a 20% off promo code to me to entice an order since I hadn’t bought anything from them in about 3 years. Perfect timing since I was going to buy it this month anyway, It worked and at $239.00 I jumped on it.

I confess to reading the instructions a obsessive number of times and even watching youtube instruction videos before running my first tests but It really was pretty easy to use. The specific reason for buying this was in response to judges notes on a wine I entered in the Cellar Masters contest suggesting Mercaptans or maybe slight Oxidation as a flaw. Until now I’ve relied on throwing in 1 campden tablet per gallon whenever I rack with no clue where I really stood. My first test on my 2016 Cab showed 27ppm SO2 but at 3.79 ph it should have been at about 80ppm. I adjusted the ph down to 3.65 and plan to retest, rack and adjust the SO2 levels next weekend. My Pinot tested at 40ppm and at 3.5 ph was just where it was supposed to be.

Now for the hard part, by next weekend I just need to become a MIT level Chemist in order to understand to formulas for calculating the amount of K-meta and how to make the correct ratio solutions to add to the wines. Seriously though, the MoreWine Guide to Red Wine Making spells out the process in detail. At least I won’t be adding chemicals blindly from now on and that has to help make better and more consistent wines.

Mike
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Old 03-20-2017, 11:18 AM   #2
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Mike,

Congrats on a great purchase. I'd been going along much the same way you've been and was blissfully ignorant for quite a while. When I started having some 'sour' tasting wines, and later some difficulty getting some to complete MLF, I broke down and got one as well. I was shocked when I measured my first wine and found it was down at 17ppm!! That won't happen again.

I also read the directions several times and watched many a YouTube video before actually opening mine and using it.
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Old 03-20-2017, 12:31 PM   #3
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Here is the formula I derived:

Gallons of wine being treated X PPM wanting to add / 156.25 = grams of SO2

an example:

5 gallons of wine x 50 ppm wanting to add / 156.25 = 1.6 grams (which is a 1/4 teaspoon)

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Old 03-20-2017, 01:53 PM   #4
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@NorCal: does that account for part of the addition being bound up? That's the part I struggle with. Need to read more. I think that's in the MoreWine manual.
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Old 03-20-2017, 02:04 PM   #5
Kraffty
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This is from Red Wine booklet, this is where I started thinking I needed to become a chemist.

PPM of “free” SO2 needed x 3.785 x Gallons (US) of wine you are adjusting
____OVER____
0.57 (the actual % of SO2 that will become “free” in your addition)

 
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Old 03-20-2017, 03:44 PM   #6
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Quote:
Originally Posted by Kraffty View Post
This is from Red Wine booklet, this is where I started thinking I needed to become a chemist.

PPM of “free” SO2 needed x 3.785 x Gallons (US) of wine you are adjusting
____OVER____
0.57 (the actual % of SO2 that will become “free” in your addition)

A couple of comments, Kraffty, if I may.

I found that equation you reproduced very annoying, because it did not tell you WHAT UNITS the result was supposed to be in. So I just looked at the Morewine! Red Wine book. You reproduced it perfectly, so it wasn't your fault! By context, evidently, the quantity you will compute in that equation is in grams.

Secondly, they don't actually mean ppm. They want you to take your ppm value and divide by 1000, i.e., they really meant parts per thousand (ppt). Sheesh.

Third: your equation and NorCals are the same, once you multiply them out. I like NorCal's version better! I'd just use his.
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Old 03-20-2017, 03:55 PM   #7
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https://vinmetrica.com/sulfite-adjus...y-so2-results/

http://srjcstaff.santarosa.edu/~jhenderson/SO2.pdf


https://www.practicalwinery.com/janfeb09/page5.htm
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Old 03-20-2017, 03:59 PM   #8
Kraffty
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Thanks Paul, I freely admit to being confused by that formula. Norcal's seems so much simpler but the one I copied is supposed to adjust for bound SO2 so, as Boatboy asked, does the @NorCal formula account for that?
Mike

 
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Old 03-20-2017, 05:10 PM   #9
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http://winemakermag.com/1301-sulfite-calculator

Try this, takes all the guess work out of it.

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Old 03-20-2017, 07:36 PM   #10
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Quote:
Originally Posted by Kraffty View Post
Thanks Paul, I freely admit to being confused by that formula. Norcal's seems so much simpler but the one I copied is supposed to adjust for bound SO2 so, as Boatboy asked, does the @NorCal formula account for that?
Mike
I understand why you said that, but I do not believe the formula you cited accounts for bound SO2. I am guessing you made that statement because your formula computes "the amount of SO2 that becomes free." But the opposite of "free" is not "bound" in this case. I am pretty sure they don't mean that the rest of it is "bound." Instead, that factor of 0.57 is to account for the portion of the k-meta that is not SO2, namely, the potassium part (and a little O).

As I say, your formula and NorCal's formula are the same formula. Whatever one does, the other will do.

I think one working assumption is that after your first SO2 addition, all the SO2 that will become bound does become bound. Thus, you have already "paid the toll" with your first addition; your first addition will NOT provide as much free SO2 as the formula predicts, but later additions WILL. Perhaps Greg or Mike or an experienced winemaker can check that statement.
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