A pool worker who added chlorine to the wrong tank at the Warrenton City Pool was injured Thursday by a chemical reaction that caused an acid cloud. Mathew Bilicki, 47, of St. Louis County, was in satisfactory condition Wednesday at St. John's Mercy Medical Center in Creve Coeur. Police Chief Greg Houdyshell said Bilicki, of Midwest Pool Management, made the mistake in a shed near the pool about 10 a.m. and inhaled fumes. The pool was closed at the time. No one else was hurt.