AJ, I finally had a moment to look back through some postings on YAN and Staggered Nutrient Additions (SNA).
@Raptor99 has a good posting
here. The paper on Advanced Nutrients in Mead-Making is very helpful in understanding the additions and why. I found it a helpful read, again
... although designed for mead, I think it applies well to winemaking. Bryan (
@winemaker81) recently had an issue with RC212 and had to add additional nutrients to overcome their needs beyond what is generally accepted. Same issue I had with the saignee / rose.
There are a lot of other posts about YAN and SNA, Deezil has some really good information as well.
Basically, and I'm typing this for my benefit as well, from
@Raptor99 's post, the SNA protocol looks like this:
- Rehydrate with GoFerm
- At 24 hours add 1/2 of the Ferm-O
- At 48 hours add the rest of the Ferm-O
- At 72 hours add 1/2 of the Ferm-K and 1/2 of the DAP
- At the 1/3 sugar break add the rest of the Ferm-K and DAP
This is where I then came into a conundrum as to what to do.... if there's a potential / persistent need for nutrients based on a sluggish fermentation and/or H2S smell (having tried to account for all other reasons), what nutrients do you add and how much. As the protocol starts with F/O and ends with DAP, I used a small amount of DAP.
When I looked back through the postings here I found some variety of how additions were made and even when. In 2010, Deezil began with GoFerm, then half the Fermaid K addition after the lag phase, then the other half at 1/3 break, then all the Fermaid O at the 1/2 - 2/3 break. Postings in the thread
here.
Around the same time, Seth discusses going up to the limits of Fermaid K, and then using as much Fermaid O as is needed, as it does not contain thiamine, and therefore you won't reach the legal limit of it in your wine. Posting of that thread
here.
In 2013, Deezil has
this amazing post on YAN, GoFerm, Fermaid K & O, and DAP with some recommendations based on Brix, and addition schedules to round the fermentation spikes into hills. Organics to start (O&K), DAP in the middle, and if low YAN grapes/must, you
could use DAP to finish although Fermaid O would be better since yeast will use-up all organic sources to the end, but only use inorganics up to 2/3 break or so. If moving from organic (Fermaids) to inorganic (DAP) the yeast can switch easily, yet moving in the opposite direction is more difficult and can create a lag.
Winemaker Magazine posted
this article from Bob Peak about YAN and completely advocates DAP. I can't find a date but I'm guessing it's old. They also have
this article from Dave Green saying that DAP should not be used as a substitute for the organic form of nitrogen.
Back to 2013, I get to lean on the wisdom of
@jswordy for having
these same conversations with Deezil and Seth now almost 10 years ago:
"Fermaid O is the ideal nutrient to use whenever you can use it. This means pretty much most things that have a somewhat decent nitrogen content. It will result in an overall really balanced steady fermentation. Fermaid O uses amino based nitrogen which the yeast can still utilize even when the yeast reaches the point that cant use DAP. Also, avoid using nutrients after the 1/2 mark unless the wine makes signs of being distressed. Then it would be fine to use something like fermaid O to help it out. But you do not want to overload it with too much because it might not use it all."
"So take home message, Fermaid O rocks when you can use it. When you can't, try using it in conjunction with Fermaid K or DAP to help make up for really large nitrogen needs. Then switch back to Fermaid O. Also, Fermaid O works better than DAP in the late phases of fermentation since it is a amino acid based nitrogen source."
Sooooo.... very long story short, as you said, I should have used Fermaid O towards the end instead of DAP.