To ensure optimum quality, brewers recommend thoroughly sanitizing the yeast brink and parts between every batch. Usually, depending on the volume of yeast, it is advisable to run off the first few gallons of yeast slurry that first flocculated to the bottom. This yeast is the least vital and would not be ideal for re-pitching. The number of generations that may be re-pitched is dependent on the strain, but over reusing may result in mutations that may eventually change the desired fermentation characteristics of the yeast strain.