Battle against the green water in the pool! Rio Olympic organizers say they will drain the bigger pool at the Maria Lenk Aquatics Center later on Saturday to get rid of the green water. The pool, where water polo and synchronized swimming will take place, will be refilled with clean water from a practice pool. The work will be done before the start of synchronized swimming scheduled for Sunday. But officials won’t take similar treatment to the adjacent diving pool, which will stay in use. Water in both pools turned green on Tuesday. Officials blamed this on treatment problems, saying water tanks ran out of some chemicals. But they say there is no health risk for athletes.