I wrote to White Labs about how much liquid English Ale yeast to use per gallon of root beer. I suggested using 1/8 teaspoon (0.6 mL) of the clumped yeast slurry at the bottom of the vial. This was the reply from White Labs:

Quote:

"Dr. White suggests doubling that rate. Yeast can have a difficult time carbonating soda because of the low nutrient value but 1.2 ml should work; the most you should need is 3ml. "Please feel free to contact us with any further questions. "Cheers!" Susan Smith White Labs

In other words Dr. White recommends at least 1/4 teaspoon of the liquid yeast slurry, up to a maximum a bit over 1/2 teaspoon.

Parsa