GPC Winter Covers 18' x 34' Blue/Black Oval Solid Winter Pool Cover for Above Ground PoolDesigned for superior durability, the GPC Winter Cover features an industry leading scrim weave that provides maximum strength and protection against harsh winter conditions. The tightly woven fabric minimizes light penetration, preventing algae growth and keeping your pool water cleaner throughout the off season. With a dual color design, the blue top absorbs heat to help with snow melting, while the black underside reduces algae buildup by blocking