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​​​​​​​TOSNA 2.0 (Tailored Organic SNA)


TOSNA has a whole new look. It has been refined and simplified after real world use in the commercial mead scene with guidance from one of the leading authorities in the wine industry today, Scott Laboratories. It has been tailored even further, taking yeast selection into consideration now as well.


All online TOSNA calculators out there will need to be updated to reflect TOSNA 2.0

Here is the calculation to determine the total amount of Fermaid-O to use:

Initial Sugar (g/L) x N requirement factor x batch size (gals) / 50 (ppm) = Total Fermaid-O (grams)


Initial Sugar (g/L)

 Brix x 10 = Sugar (g/L)
*1° Brix ≈ 10 g/L sugar


Nitrogen(N) Requirement Factor

For Low N requiring strains, Sugar (g/L) x 0.75 = YAN requirement

For Medium N requiring strains, Sugar (g/L) x 0.90 = YAN requirement

For High N requiring strains, Sugar (g/L) x 1.25 = YAN requirement

*Sugar (g/L) = Brix x 10

​*Factors sourced from Scott Labs fermentation handbook 2016


Common yeasts w/ Low N needs, 71B, DV10 , D47, EC1118

Common yeasts w/ Medium N needs, D21, D254, D80, V1116

Common yeasts w/ High Nitrogen needs, CY3079, RC212

*Information on additional yeast strains can be found on Lallemand's website.


50 (ppm) Effectiveness using Fermaid-O

1g/gal of Fermaid-O = 50ppm (or mg) of N/L effectiveness

*It is recommended to invest in a good grams scale


Nutrient Addition Schedule / How to add your Fermaid-O

Once you get your total Fermaid-O to be used based on the TOSNA formula above, you can divide the total by 4 to get the grams of each individual nutrient addition you will be adding, as follows:


​- The first nutrient addition happens 24-hours after yeast pitch. 
- Then at the 48 & 72 hour marks after yeast pitch.
- Final nutrient addition is on Day 7 after yeast pitch, or when fermentation has reached its 1/3 sugar break, whichever comes first.​​


The above mentioned TOSNA nutrient calculations are intended for use in traditional mead recipes, meaning, meads that you are fermenting honey without fruit. When fermenting with fruit and/or fruit juice, the amount of Fermaid-O can be cut by half.​