This recipe is for a hard seltzer. nNoted from thebeerjunkier.com suggestions.
Water: if using muni water use campden tablet to remove chlorine.do not need to optimize sodium, chlorine, sulfates, etc, but need 50-150 calcium for taste and acid to lower pH. suggest <5ppm sodium, <50 ppm bicarbonates, sulfates and chlorides <100ppm.
sweetener: 100% cane or beet sugar. 11 oz sugar per gallon.
Because you do not have the enzymes in the malt to lower the pH to the low 5’s, you may need to add a small amount of phosphoric or lactic acid. A pH in the low 5’s is essential for brewer’s yeast health. The optimal pH for wine yeast is around 3.8. There is no buffering capacity without the malts, so add very little amounts at a time.
yeast but use a strain that ferments quickly, is highly attenuative, and is very neutral. You can use brewer’s yeast, wine yeast, or distiller’s yeast. recommend pitching around 20% more yeast for hard seltzer than for ale.
Need yeast nutrient. In addition to this, we also recommend adding diammonium phosphate (DAP). No more than 3/4 grams per gallon of hard seltzer, or the yeast may experience overstimulation. Check yeast nutrient if they use DAP adjust accordingly. When adding the nutrients, multiple doses – once with the yeast pitch, one the following day, and another one 2 days later. If it slows down well before you approach 1.000, add another dose. If it is actively fermenting after the first two doses, feel free to hold off on the third dose until it slows down.
Critical items in my mind: water, fermentation/yeast nutrient, carbonation.