Pool cove is a foam or plastic molding installed along the inside base of your above ground pool wall, where the wall meets the floor. Without pool cove, the liner must fold around a sharp 90° corner, a stress point that can develop pinhole leaks over time. Pool cove creates a smooth, curved transition (typically 45°) so the liner lies flat without tension at the base. Always install pool cove before placing a new liner for maximum liner life.