Complex sentence: Francisco Pancho Medrano (1920--2002) remembers as a child only being allowed to swim in the pool early in the day when it was cold and before the pool was drained from the previous day and refilled with fresh water for the White swimmers.
Split into simpler sentences: Francisco Pancho Medrano (1920--2002) remembers as a child being allowed to swim in the pool only early in the day. It was cold then and it was before the pool was drained from the previous day and refilled with fresh water for White swimmers.