Water that is "hard" contains large amounts of dissolved minerals such as magnesium and calcium. Although it is not harmful to your health, it can build up in products and equipment that have water flowing through them on a regular basis. Over time this build up can became a problem because it can cause components to corrode and malfunction, ultimately shortening the life of your products. Since evaporative coolers use water this is a common issue.
You can treat the problem with the Port-A-Cool MK-47 protective additive. It's very easy to use, just add it to the water tank. Then you'll be able to prevent the mineral build up ensuring that your unit is operating at optimal efficiency, thus cooling effectively. The additive works with any model and ends up paying for itself since it with extend the life of the unit.
Port A Cool Evaporative Cooling Units are Manufactured by Port A Cool, LLC., Center, Texas U.S.A.