My 13th brew session was an extract brew West Coast IPA. I had some issues during the brew with my equipment in cooling the wort that resulted in a foamy mess. (The transfer pump was unrestricted which made the flow too rapid) I had estimated a batch size of 7 gallons in a 10 gallon fermenter which was also an equipment change. In a desire to increase my batch size, I increased the fermenter size, using a 10 white garbage can with a lid. Because I had previous issues with blow outs, I felt the additional room would give my beer more room to ferment. I used corn syrup for my priming sugar to achieve a 2.5% carbonation. The end results were, my vapor lock never bubbled and yet my ABV is at 6.59% when the recipe expected 4.95%. The flavor is what I was expecting. However the beer while carbonated, produce very little if any head. The lacing is as expected. The only other factor I could not reconcile was the yeast amount. I used one packet of Lallemand's West Coast Ale yeast which is the same I have used for 5 - 6 gallon batches that came out well. So my question is essentially, when and how do I scale up my yeast amounts?