Breg® Ice Bags are extremely useful for extending the length of time the unit will circulate cold water. Simple add water to the bags and freeze them, and add them to your cold therapy cooler. The recirculating water stays colder for longer. Sold in a pack of 12. Keep half in the feezer and half in the unit and rotate as needed for constant cold therapy.
FDA Warning - Please do not put the cold therapy pad directly on bare skin due to risk of injury.
Not cheap but much more efficient than ice cubes.