Turtle Creek Farm, Inc. Stock Tank Secret, Brown, 9" x 7" Keep your water tanks clean and algae free! 100% organic barley straw helps keep stock tanks clean and drinking water palatable for up to two months. When barley straw is added to the water, it begins to decay. This decaying process releases lignin which then interacts with algae and causes it to die. Completely safe and effective treatment contains no chemicals, pesticides, or herbicides; no toxic side effects. Can be used with cattle, goats, sheep, swine, all breeds of horses, poultry, fish and even exotic animals. Also great for automatic waterers,