Senior Airman Matthew Atton, 28th Civil Engineer Squadron water and fuels maintenance technician, turns off water flow to the Bellamy Fitness Center’s swimming pool strainer during routine maintenance on Ellsworth Air Force Base, S.D., Feb. 3, 2012. The water’s pH levels are tested to determine if they need more acidic or basic chemicals to ensure a safe and clean pool for swimmers. (U.S. Air Force photo by Airman 1st Class Zachary Hada/Released)