Evaporative cool mist humidifiers cannot run without the use of a wick filter.
The harder the water, the shorter the filter life. This is because minerals will get trapped in the filter over time and cause the filter to lose its ability to wick. We recommend you replace your filter every 4-6 weeks, depending on usage and hardness of water. In some evaporative cool mist humidifiers we have included a Filter Check indicator that will indicate when the filter needs changing
The Holmes HWF100CS (E) Wick Humidifier Filter features an exclusive ARM & HAMMER Baking Soda layer to help remove household odors.