Its really interesting. I was reading the section on fermentation (chapter 4) from the book, 'Yeast, The practical guide to beer fermentation', by Chris White and Jamil Zainsheff and essentially yeast need, sugar, nitrogen, vitamins, phosphorous and trace metals (and oxygen of course) Nitrogen makes up about 10% dry weight of a yeast cell, Phosphorous about 5%. Anything with ammonium sulphate and diaminophosphate will give adequate nitrogen and phosphate.
One thing I am reticent about using is RO water (actually I have access to unlimited amounts of the even purer dionised water because of my work) because it essentially strips the water of trace elements (I think, please correct me if I am wrong) which yeast need to synthesize certain components and processes. Zinc is often in rather short supply.
I have been adding yeast nutrient in the whirpool and sometimes when pitching with pretty good results, yeast seem lively and healthy and beers are usually finishing out in 5-8 days. Yeast will sometimes actually chelate trace metals itself in the cytoplasm as a kind of defense mechanism. So whats Robbie the low oxygen enthusiastic learner supposed to make of all of this?
1.add a little more calcium than you would to account for the chelation effect of Brewtan B
(60 ppm Ca 2+ for the beers stabilised with gallotannins. It
proved important to add extra calcium at mashing-in in order to
compensate for the expected chelating effect of gallotannins)
https://www.researchgate.net/public...oiling_by_addition_of_gallotannins_andor_PVPP
2. Use a yeast nutrient to provide enough non organic nitrogen and phosphate (ammonium sulphate and diaminophosphate)
3. Think about adding zinc at the end of th boil 0.2 - 0.3 mg/l zinc chloride according to Dr. Chris White (Yeast, The practical guide to beer fermentation chapter 4)
4. Consider a specialist and patented solution like Servomyces which is essentially yeast that are grown in a metal ion rich environment, the yeast take up all the metals they can in the yeast wall which prevents them from chelation when added to the wort! Panic over, problem solved.