The "Do Not Dive" warning at the shallow end of the Sanderson Center's natatorium could have applied recently to the entire 500,000-gallon pool. Lifeguard Crofton Sloan and the swimming facility's patrons were left high and dry while a pipe valve was replaced. The refill process now under way should take about two days to complete. The pool officially reopens Aug. 11. For additional information, telephone 662-325-7946.