Originally Posted by Glibbidy
IIRC zinc may used as a yeast nutrient, However, the dosage amount I don't recall.
As far as aquiring it....anywhere you can find vitamins.
EDIT: I did some googling and found this on zinc:
0.1-0.3mg/l and up to 0.5 mg/l being maximum
The key to adding zinc is to be careful of the form that it is added in. Simply adding ZnCl2 or ZnSO4 in the appropriate concentrations will not work (unfortunately) since it will be absorbed into the trub. You need to add a biologically abundant form of zinc...a zinc chelate like Zinc citrate or Zinc gluconate.
More details can be found in Bromberg, Susan K, et al. Requirements for Zinc, Manganese, Calcium, and Magnesium in Wort. JASBC, 6/11/97.