 Urolytic bacteria have a pH optimum of approximately 8.3 and litter amendments lower the litter surface pH to below 4.0 for a short period of time, usually between 3–5 days depending on the litter amendment.There are several different types of acidifiers, such as alum, acidified liquid alum, sodium bisulfate, ferric sulfate, and sulfuric acid, that have been used by the poultry industry.These products vary in effectiveness as the pH is raised by the activity of the poultry within a couple of weeks.