Fermaid-O calculation - Tosna 3 broken?

[meadgaard]

Hey, I'm a beginner at making mead and for my next batch I plan to use Fermaid-O nutrient only.

Calculation parameters:
OG 1.100
FG 1.000
BRIX 23.77
Total must volume 1 gallon = 3.785 liters
Medium yeast nutrient factor, NF = 9
Fermaid-O nutrient only


Calculating by hand using information from Scotlabs Fermentation Handbook 2024 and Fermaid-O data sheets:

YAN needed, milligrams per liter (ppm) = BRIX x NF = 23.77 x 9 = 214 milligrams per liter
Total YAN needed, milligrams = 214 mg/L x 3.785 L = 810 miliigrams

Fermaid-O (real YAN), 40 milligrams YAN per gram nutrient
Total Fermaid-O = 810 / 40 = 20.3 grams


TOSNA 2 calculator at meadmakr says a total of 21.6 grams Fermaid-O.
TOSNA 3 at meadmaderight says a total of 4.3 grams.


TOSNA 2 at meadmakr seems to agree with my hand calculation, but using TOSNA 3 at meadmaderight seems to give only 1/5 of the nutrient needed.

Is the TOSNA 3 calculator broken or did I get my hand calculation method wrong?

 

[meadgaard]

The Fermaid-O calculator in meadtools recipe builder also seems broken, giving 7.3 grams. It reports 235 ppm YAN needed, but uses the same value for total YAN. Maybe there is a confusion of what ppm really is, milligrams per liter solution. The calculated ppm should be multiplied by total volume in liters, to get the total milligrams YAN needed, I guess.

 

[MightyMosin]

You had me curious, so I pulled up some recipes and pinched them in to compare to what I had listed as the nutrients from when I did them originally.

Some of them come out the same with TOSNA 3.0 and others seem to be different. Maybe based on the yeast selected, but it isn't all coming up the same. Unfortunately, I didn't make notes about which TOSNA those were based on.

A recipe from March of 2023 had these basics:
6.5 gallon
OG 1.090
Viti Levur 58W3
18.8 g Go-Ferm in 176ml water
7g Yeast
25.2g Ferm-O needed

TOSNA 3.0 today:
6.5 gallon
OG 1.090
Viti Levur 58W3
16.3 g Go-Ferm in 326ml water
13g Yeast
25.1g Ferm-O needed

Looking at it, the water listed for the Go-Ferm in 2023 was not accurate as it should have been 376ml for that amount. Nutrients were about the same though recommended yeast amount is very different.

 

[meadgaard]

You had me curious, so I pulled up some recipes and pinched them in to compare to what I had listed as the nutrients from when I did them originally.

Some of them come out the same with TOSNA 3.0 and others seem to be different. Maybe based on the yeast selected, but it isn't all coming up the same. Unfortunately, I didn't make notes about which TOSNA those were based on.

A recipe from March of 2023 had these basics:
6.5 gallon
OG 1.090
Viti Levur 58W3
18.8 g Go-Ferm in 176ml water
7g Yeast
25.2g Ferm-O needed

TOSNA 3.0 today:
6.5 gallon
OG 1.090
Viti Levur 58W3
16.3 g Go-Ferm in 326ml water
13g Yeast
25.1g Ferm-O needed

Looking at it, the water listed for the Go-Ferm in 2023 was not accurate as it should have been 376ml for that amount. Nutrients were about the same though recommended yeast amount is very different.

Let's see what my calculation would suggest:

6.5 gallon = 6.5 x 3.785 = 24.6 liters
OG 1.090 = 21.6 BRIX (if fermented dry)
Low yeast nutrient factor, NF = 7.5

YAN needed milligrams per liter (ppm) = BRIX x NF = 21.6 x 7.5 = 162 milligrams per liter
Total YAN needed = 162 x 24.6 = 3985 milligrams
Fermaid-O contains 40 milligrams YAN per gram: 3985 / 40 = 99.6 grams

Dont know if Go-Ferm contribute any significant amount of YAN or not.


Spent half day searching the web and found several other sources explaining YAN calculation and can conclude that my hand calculation is indeed correct. The same calculation method can be applied for other YAN nutrients aswell. Fermaid-K got 100 milligrams YAN per gram and DAP got 210 milligrams YAN per gram.

Using DAP instead of Fermaid-O in the calculation: 3985 / 210 = 19 grams.

The yeast nutrient factors are: Low 7.5, Medium 9, High 12.5 and Very High (kveik) 18.

 

[DBhomebrew]

Dont know if Go-Ferm contribute any significant amount of YAN or not.

Yes

 

[MightyMosin]

YAN needed milligrams per liter (ppm) = BRIX x NF = 21.6 x 7.5 = 162 milligrams per liter
Total YAN needed = 162 x 24.6 = 3985 milligrams
Fermaid-O contains 40 milligrams YAN per gram: 3985 / 40 = 99.6 grams

Dont know if Go-Ferm contribute any significant amount of YAN or not.

99.6g of Fermaid-O would seem an extremely high amount.

 

[meadgaard]

99.6g of Fermaid-O would seem an extremely high amount.

Found the amount of YAN in Go-Ferm, 33 milligrams per gram.

Calculation excluding the Go-Ferm contribution:

Total YAN needed: 3985 milligrams

Go-Ferm 16.3 gram: 16.3 x 33 = 538 milligrams
Subtracting Go-Ferm from total YAN: 3985 - 538 = 3447 milligrams

Fermaid-O: 3447 / 40 = 86.2 grams

Using DAP instead: 3447 / 210 = 16.4 grams

 

[meadgaard]

There is a 4X efficiency factor when using Fermaid-O instead of inorganic nutrients like DAP.

Simply dividing the calculated Fermaid-O grams by 4: 86.2 / 4 = 21.6 grams

So Tosna 2 does not include Go-Ferm in the calculation, Tosna 3 includes Go-Ferm and have Fermaid-O at 4 x 40 = 160 milligrams YAN per gram.