A storage tray arrangement for storing cable slack in fiber optic systems includes a vertically oriented frame and at least one tray mounted to the frame in a vertical plane parallel to the frame. There is a mounting construction that permits the tray to be pivotally secured to the frame. The mounting construction permits the tray to be selectively pivoted relative to the frame within the vertical plane. In preferred arrangements, the trays are mounted as tray sets having at least two trays mounted to a common pivot post. Particular preferred trays include trays having scalloped side walls. Methods for storing cable slack utilize trays and mounting arrangements as described herein.