Originally Posted by Matteo57
So it says I need 2 vials and a 1.17L starter for 7.5g batch at OG of 1.070. Do I really need 2 vials or can I feed the yeast to make it work for a 7.5g batch at 1.070 OG?
I get different figures than you. For a 1.070 brew at 7.5 gal., you need 362 billion cells of yeast. You can obtain this by a number of ways; 2 packs of 11 gm. dry, 4 packs of liquid yeast (harvest/production date must be today), or 2 packs of liquid (harvest/production date today) in a 3.13 liter starter, or 177 mL of yeast slurry (harvest date is today). Notice that the harvest date is important. If your liquid yeast samples whether from Wyeast or White Labs or from washed yeast happens to be aged somewhat will change the amount needed to obtain that 362 billion cell number. So it's good to have fresh yeast. If it isn't, plan on using more. Dry yeast will stay the same.
I am not familiar with stepping up a starter. I either use dry yeast or use multiple washed yeast slurry samples in usually a 1500 mL. starter. This is why I like to always make 8 pint jars of washed yeast from generally every beer I make. I'm cheap I guess.
Hope this helps.