Am I calculating this correctly (S02 with Vinmetrica)

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Siwash

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Hey folks, I have done these tests before but still pretty novice with the Vinmetrica. I am posting this b/c I am unsure if I got the right reading and/or did the correct calculation. I used a 5ml amount of So2 titrant solution, 25 ML of wine and 2 ml of So2 acid reagent - I believe I followed the procedures as per instructions. I came up with 44 by subtracting 2.8 ml from 5 ml (5 - 2.8 = 2.2) - this was the volume of titrant used (so only 2.2 remained in the syringe) - is this the correct calculation? From there I 20 x 2.2 ml and that gave me 44. 44 is actually where my So2 reading should be as my PH is at 3.55. How is it possible that I have enough So2 in my wine since I didn't add any So2 since September, and that was to the must when I added it to clean the slate of the native yeast prior innoculting it with commercial yeast. Last year I had to add So2 after doing this test. My wine went through a 2 month+ malolactic fermentation that ended in December.

Did I do this correctly? Should I do it again? Thoughts? Are my methods incorrect? thanks!
 

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NorCal

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I did my wines today. Your calculation is incorrect; the free SO2 is 20 X the M.L. of titrant that you used, not what you have left in the syringe. Confirmed with the instructions. IMG_1382.jpg
 
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I did my wines today. Your calculation is incorrect; the free SO2 is 20 X the M.L. of titrant that you used, not what you have left in the syringe. Confirmed with the instructions. View attachment 45742

It has always been my understanding the reading is taken from the top of the cone in the syringe and not the point. Which would make it 2.2 ml used.
 

NorCal

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(so only 2.2 remained in the syringe) - is this the correct calculation? From there I 20 x 2.2 ml and that gave me 44.

I’m a bit confused. You said 2.2 remained in the syringe, which means you used 2.8. If 2.2 remained in the syringe, how did you only use 2.2?
 
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I’m a bit confused. You said 2.2 remained in the syringe, which means you used 2.8. If 2.2 remained in the syringe, how did you only use 2.2?

I guess that was my confusion. I didn't pay enough attention to what was written. I looked at the syringe. He did only use 2.2 ml, 2.8 was left in the syringe.
 

Siwash

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I started with 5ml as per instruction. What was left in the syringe was 2.8 ml! So 20 x 2.2 = 44 (or do I multiply 20 x 2.8?) Either way it seems like I have enough free So2

I had a busy week so I didn't get back sooner... wine is still sitting in demis untouched since last test. I have 30 min this morning... going to try test again..
 

wxtrendsguy

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Please if using a vinmetrica get rid of that junky 5 ml turkey baster and get a 100ml graduated burret. Your titrations will be far more accurate and controlled. In any case I have had my vinmetrica for years and it gives me almost 100% of the time a free SO2 within 1 ppm of the lab results. If you used 2.2 ml of titrant your free SO2 is 44 ppm which is more than enough SO2 for a wine with a ph of 3.55.

Since I make commercial wine let me comment that many home and commercial winemakers add way too much sulfur. My highly compensated consultant from France told me to lower my SO2 a whole lot. Molecular SO2 at 0.8 or even 0.5 was far too high. I should be using 0.4 for dry whites and 0.35 for dry reds and basically never have my free SO2 above 50 ppm. Sweeter wines have to go higher but if they are dry than high levels of SO2 are not needed. We just bottled a cab sauv with a ph of 4.0, yea hard to believe but the acid was very nicely in balance and flavor was perfect...total free SO2 at bottling was 50ppm. High ph but still plenty of acid is a common issue here in PA due I believe to elevated potassium levels in the soil...so we deal with it all the time. 100,000 bottles later and we have yet to come across a serious problem following our SO2 protocol.
 

Siwash

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I figured out what went wrong... I forgot to add the 2 ml of acid! D'Oh!! I did the test again and It was 12 PPM. So I added about 2,7 grams of Kmeta per 54L demi to bring it up to 45 PPM Thanks!
 

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