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Several weeks ago I purchased the Vinmetrica SC-100A SO2 tester. For myself, it was a purchase worth the money as my pyments have been using more expensive ingredients and protecting that ingredient cost became a deciding factor.
This is a bit of a pricy (~$360) test equipment that has a single job and that is to measure unbound SO2 in your wine. This is a stripped down version of its big brother the SC-300 that handles many more duties and is close to double the cost of the 100A. If I needed total acidity and pH in a meter than the big brother would have been the way to go. I'm happy with my simple pH meter.
I eventually decided to purchase this after having a few different meads that experienced some wine faults that I suspected was related to insufficient SO2 levels. The short story is that I was absolutely low on free SO2 levels and that was because I should have replaced my K-Meta sooner than I did. The problem is that I didn't know that my K-Meta was basically dead. I tested a mead that had been recently racked over K-Meta and where I was expecting free SO2 in the 30ppm range, I was hitting something like 5 ppm.
Here's a decent video on using the tester.
The use of a stir plate isn't necessary if you constantly swirl, but in my experience I don't see doing it without a stir plate. They're pretty inexpensive.
Depending upon the pH of your wine/mead, you will know what your optimal SO2 levels should be. Based on the pH, you'll see that the higher the pH the higher the amount of free SO2 is needed.
You will generally want to maintain a molecular SO2 of 0.8 parts per million. Molecular SO2 is dependent on the pH of the wine. The higher the pH, the more SO2 is required to achieve 0.8ppm molecular SO2. Below is a chart showing the required free SO2 necessary to achieve 0.8ppm molecular SO2.
pH Free SO2
-----------------
2.90 11
2.95 12
3.00 13
3.05 15
3.10 16
3.15 19
3.20 21
3.25 23
3.30 26
3.35 29
3.40 32
3.45 37
3.50 40
3.55 46
3.60 50
3.65 57
3.70 63
3.75 72
3.80 79
3.85 91
3.90 99
3.95 114
4.0 125
How much K-Meta to add:
Gallons x 3.785 x (Free SO needed from chart above - Tested Free SO2) X 2
divide above total by (1000*0.576) The 0.576 is the fraction of SO2 in K-Meta that equals grams of K-Meta to use.
---------------
Using Liter instead:
Liters x (Free SO needed from chart above - Tested Free SO2) X 0.0066
That equals grams of K-Meta to use.
Hope this ends up being helpful to some of you.
This is a bit of a pricy (~$360) test equipment that has a single job and that is to measure unbound SO2 in your wine. This is a stripped down version of its big brother the SC-300 that handles many more duties and is close to double the cost of the 100A. If I needed total acidity and pH in a meter than the big brother would have been the way to go. I'm happy with my simple pH meter.
I eventually decided to purchase this after having a few different meads that experienced some wine faults that I suspected was related to insufficient SO2 levels. The short story is that I was absolutely low on free SO2 levels and that was because I should have replaced my K-Meta sooner than I did. The problem is that I didn't know that my K-Meta was basically dead. I tested a mead that had been recently racked over K-Meta and where I was expecting free SO2 in the 30ppm range, I was hitting something like 5 ppm.
Here's a decent video on using the tester.
The use of a stir plate isn't necessary if you constantly swirl, but in my experience I don't see doing it without a stir plate. They're pretty inexpensive.
Depending upon the pH of your wine/mead, you will know what your optimal SO2 levels should be. Based on the pH, you'll see that the higher the pH the higher the amount of free SO2 is needed.
You will generally want to maintain a molecular SO2 of 0.8 parts per million. Molecular SO2 is dependent on the pH of the wine. The higher the pH, the more SO2 is required to achieve 0.8ppm molecular SO2. Below is a chart showing the required free SO2 necessary to achieve 0.8ppm molecular SO2.
pH Free SO2
-----------------
2.90 11
2.95 12
3.00 13
3.05 15
3.10 16
3.15 19
3.20 21
3.25 23
3.30 26
3.35 29
3.40 32
3.45 37
3.50 40
3.55 46
3.60 50
3.65 57
3.70 63
3.75 72
3.80 79
3.85 91
3.90 99
3.95 114
4.0 125
How much K-Meta to add:
Gallons x 3.785 x (Free SO needed from chart above - Tested Free SO2) X 2
divide above total by (1000*0.576) The 0.576 is the fraction of SO2 in K-Meta that equals grams of K-Meta to use.
---------------
Using Liter instead:
Liters x (Free SO needed from chart above - Tested Free SO2) X 0.0066
That equals grams of K-Meta to use.
- (0.0066): This constant is derived from the conversion factors: 3.785 (gallons to liters), 1000 (mg/L to g/L), and 0.576 (the fraction of SO2 in KMBS).
Hope this ends up being helpful to some of you.
Last edited:
