For use in the optional fourth product dispenser if additional souring is required due to local water conditions. Contains a unique blend of powerful ingredients that provide souring capabilities to bring linens to skin-compatible pH and maximize protection against yellowing of linen and rust stains caused by high iron content in water. The sour has anti-chlor agents that protect your linen from chlorine damage, prolonging linen life, and is effective on all fabrics. For use with Aquanomic low temperature solid products and the Smart Wash Process.