Why are the filters in my evaporative humidifier changing color and getting moldy?

The color change is due to the components of the tap water or air. The filters change color more quickly depending on the water quality. This is not very aesthetic, but as long as it is not mold, it is harmless. On the other hand, filters affected by mold should be thrown away and the device should be cleaned thoroughly. If you have recently changed the filters, you can rinse them, turn them over and continue using them. If you have been using the filters for more than 2 months, replace them with new ones. Please note that the color of the filters has no influence on the normal operation of the humidifier.