The Better Pond Stock Tank Cleaner Barley Bale aids in maintaining freshwater in animal water tanks. Naturally remove algae without adding any chemicals to drinking water. This treatment is perfect for horses, livestock, cattle, swine, poultry, goats, sheep, fish and exotic animals. This barley bale can be used for automatic waterers, birdbaths, fountains, stock tanks, and ponds. Lasts up to 6 months.