I always use yeast nutrient, fermaid k and fermaid o in grape wine. And i swap out the ec1118 that the kits come with for rc212 (for reds) which is a bit of a nutrient hog, so i always add a bit of fermaid k at the begining and some fermaid o near the end.Is there ever a reason to add additional yeast nutrients during primary? I added some when I pitched....just wondering if anyone ever adds more, if so why?
Yeah i just used some 71b-1122 in some high acid must, it finished well with some nutrients. Are you doing a kit or grapes? 71b will metabolize 30% of the malic acid, kits are balanced before you open it. Not sure id recommend 71b for a kit, youll be changing the balanced must, i only use 71b if the must has high acid content.I've been using 71B-1122 on reds lately. It started out strong, now has slowed down. Hence the question about adding more nutrients.....thought maybe it needed a little food.
Micronutrients are nice to have in a ferment but what is really needed is nitrogen, which is the component you really need in nutrient. Fresh juice musts from fruit are not low YAN (yeast assimiliable nitrogen) musts. So for most ferments from fresh juice, you can assume that the beginning YAN is 150mg/liter. The bare minimum of fermentable nitrogen needed for fermentation is 140mg/L. Normal range is between 225 and 275 mg/L. So as you can see, you need to add enough nitrogen(nutrient) to bring up the YAN to a level where the yeast have the nitrogen that they require.
So you need to not only give your ferments enough nitrogen, but you need to add it when the yeast is looking for it. As new populations of yeast cells are generated, these new yeast look for nitrogen as part of their nutrient needs. The best way to do this is to step-feed nutrient. Take the entire doseage and divide it in half. With energizer, you'd add the first half 24 hours after pitching the yeast. And the second half at 50% sugar depletion. If you do this, you won't have H2S problems. H2S is almost exclusively a problem of lack of nitrogen--barring any residual sulpher spraying on the fruit in the orchard or vineyard.
Normal doseage of nutrient is 1 tsp. per gallon.