Dirty stocks tanks are a common problem in livestock management. Not only do they become unsightly, but also unsanitary. Over time, dirty water becomes a breeding ground for mosquitoes and other waterborne insects. In many circumstances, the livestock will no longer consume the water, which can lead to dehydration or even colic in horses. Other products currently available to keep stock tanks clean may present an inconvenience. Most existing products contain chemicals, which may be harmful to animals. Therefore, animals must be taken off the tank; the tank must be emptied, scrubbed and then rewashed, rinsed and filled with fresh water. The process is time consuming, taking up to several hours, dependent on the size of the tank. It is also messy, as the water removed from the dirty tanks makes the surrounding area muddy. Through Internet research, the inventors learned barley straw has been used to treat lakes and streams in the United Kingdom for decades. Further research showed that many U.S. universities had completed studies on barley straw as a water treatment. During product development, to assure Stock Tank Secret was completely safe, organically grown barley straw was used and then processed to make it suitable for stock tanks. The processed barley straw was placed in burlap bags. Several bags were placed in stock tanks and automatic waterers for horses. After about a week, the debris in the tanks turned black. After scooping the debris out, the tanks stayed clean for more than 60 days. There were no ill effects noted on any of the horses consuming water from the tanks. When the tank started to look dirty, a fresh bag was placed into the water and the water became clean again within a few days. A sample of the water containing the dead algae was sent to Kansas State University for toxicology testing. There was no negative reaction.