Depending on how hard your water is the mineral and scale build up in the cooler might be extreme. The scale build up on the cooling pads reduces the performance of Evaporative Air Cooler. Other concerns include water cleanliness and muggy smell. You might consider a combination of these products to help keep the cooler lasting longer and working better than ever before.
D-Scale and evaporative cooler cleaner:
When an evaporative cooler gets mineral and scale buildup it might be time to use a cleaner or some form of de-scaler. This will help the cooling pads last longer. Also, with the pads cleaned it can help keep the air temperature cooler because more water can be absorbed into the pads. For most cleaners you pour a certain amount of cleaner into the evaporative cooler pan with the water and run on pump mode for about 20 minutes. The scale and minerals will get washed out into the pan for you to drain out. Then drain the water, flush it out and refill the pan with clean water.
If you want to keep the water in the evaporative air cooler clean throughout the summer then try installing a purge pump. This will clean the water in the cooler automatically every 8 hours or so by pumping a percentage of the water out of the pan. Purge pumps are easy to hook up since they just plug into the existing cooler pump. Keep your water and air fresh by having the old water pumped out and clean water coming in and through the pads. The discarded water could be utilized by a nearby garden, plants or trees if you want to avoid wasting water.
Filter incoming water with an inline filter. Preventing scale buildup is much easier than removing hard water deposits. So how about a nice in line filter that will filter the water coming into your swamp cooler before it gets pumped through the pads. This can reduce scale and lime deposits leading to longer lasting pads. Inline filters can be installed anywhere on the water source before the water goes into the evaporative cooler. If you have really hard water in your area this type of filter can help prevent extra build up on your evaporative cooler and pads.
Zinc Anode Rod:
Keep the musty cooler smell from building up with a Zinc Anode Rod. These are great for controlling rust, mold, and mildew in an evaporative air cooler. Some coolers can begin to smell and this could be due to growing bacteria in the cooler. Water, warm days, and stagnant water are a perfect mold breeding ground. Control this by adding a zinc anode rod which inhibits the bad stuff from growing. Keeping growth under control will help keep your air quality safe and the cool air smelling fresher.
Drop in tablets are another way to help prevent mineral and scale buildup. These are time released tablets that you can drop into the cooler pan and leave. They are a lot like using the cooler cleaner but you leave these in and they require no measuring. If your evaporative coolers pads are already clean you might consider this as a good combination with a purge pump to give you better water with little or no buildup.