Trying to calculate nutrient amount

I think there's a problem with your math. Per the TOSNA protocol, I took your OG of 1.088 and converted to 21.1 brix. That (as you said) requires 200 mg N/L for your batch. So you take 200, divide by 50, and multiply by your starting gallons (5), which tells you you need 20 grams of Fermaid-O total. Divide this by 4, and you get 5g of Fermaid-O at each of the scheduled nutrient additions. Your total of 3.8g would be far short of this.

Beyond that, coming up with an equivalent use of Fermaid-K and/or DAP seems to me to challenge the TOSNA protocol at its core. Fermaid-K and DAP function differently than Fermaid-O, and we already know pretty definitively that DAP cannot be picked up by yeast once the ABV has passed 9%. Based on your OG, you could end up a little higher than that, but not much. My greater concern would be that you may overestimate the DAP/Fermaid-K equivalence to Fermaid-O, and put way too much in there, with the result being that you will taste it in the final product.

Perhaps someone far more educated on the actual efficiency of the YAN you get from Fermaid-K and DAP could chime in to help you with those estimations. But be warned, there is currently a rather scholarly conversation going on regarding the "true" efficiency of YAN provided by DAP versus other organic sources, such as Fermaid-O. So there will be some speculation going on. Me personally? I tossed all my DAP and Fermaid-K, and I've gone exclusively to Fermaid-O. And when I've followed the TOSNA protocol to the letter, it's been faithfully successful for me.

djsxxx said:

So I'm planning on starting my first large mead batch, 19 L. It is a bit of an experiment as I'm going to be trying out the Wyeast Sweet Mead yeast. Mentioned this in another thread and a lot of people have said its a tough yeast to please.

Rough plan:

OG: 1.0875
Volume: 19 L
ABV: 11.61%
Honey: 5.55 Kg

The thing I'm struggling with is trying to work out how much nutrient I'm meant to use.

I've used the TOSNA protocol as a guide to how much mg N/L I need, and from this work out how much nutrient to use. I have DAP and Fermaid-K (only 24g of the Fermaid)

So, TOSNA recommends 200 mg N/L (for my OG)

That's a total of 3,800 mg N for a 19 L batch.

(The following figures are numbers I found on the internet, no idea if they are accurate)

DAP (Diammonium Phosphate)

25g/HL = 50mg/L N
0.25g/L = 50mg/L N
1g/L = 200mg/L N


Fermaid K.

25g/HL = 25 mg/L N
0.25g/L = 25 mg/L N
1g/L = 100 mg/L N

If those numbers are correct, if I use all my Fermaid-K, 24g, that leaves me with 7g of DAP to be used to make up the rest of the N.

Does that sounds right, or am I way off here?

Click to expand...

Try this to see if it will help

This is my approach (and although there are similarities to other nutrient methodologies, we do differ somewhat). It agrees for the most part with the recommendations of Lallemand and other commercial yeast manufacturers.

First, I make an assumption that the honey that I use in any of my musts provides negligible amounts of YAN.

Next, I determine what (if any) fruit I will use in primary fermentation.

Then, I try to find out (for melomels) how much YAN is present in the fruit I plan to use (measured in ppm, for the given volume of fruit I'll add in primary). If I can't find info on YAN for my particular fruit, I assume a baseline value of 100 ppm. That's close enough for gov't (and mead) work.

Then I work out the dilution of that fruit-supplied YAN in my total volume of must. If for example I am mixing up a 5 gallon batch of must, and one gallon is pure fruit at 100 ppm, then I will dilute by a ratio of 1/5, so the net YAN in my fully mixed must is 100 * 1/5, or 20 ppm.

I next find the nitrogen requirements of my yeast. For most commercial yeast strains we only know if the demand is low, medium or high. For low demand yeasts, I ensure that the total YAN is 225 ppm. For medium demand yeasts, I ensure that the total YAN is 300 ppm. For high demand yeasts, I ensure that the total YAN is 350 ppm. These are numbers that I've found through trial and (mostly) error that will produce clean ferments with minimal H2S production in my meads.

Note: Those values are what I use for "normal strength" meads, which for me are musts that range in initial gravity from 1.080 to 1.100 (Initial Brix range of 20 to 24). For initial Brix of 24 to 27 (SG from 1.101 to 1.115) I multiply my normal strength numbers by 1.1. For Brix from 27 to 32 (SG from 1.116 to 1.140) I multiply the normal strength numbers by 1.25. For initial gravities in excess of that, I wing it.

I calculate how much Fermaid-K and DAP to use knowing that Fermaid-K has 13% YAN by weight and DAP is 21% YAN by weight. Another way to express the YAN content of those is that 1 gram of Fermaid-K provides 130 ppm of YAN to a single liter of must, and 1 gram of DAP provides 210 ppm of YAN to a liter of must.