Holmes A Humidifier Filter HWF62 improves the efficiency of your humidifier by trapping mineral deposits from the water. This triple-layer humidifier filter helps control dust and dirt build-up and prevents impurities from spreading by passing air through the filter, also remove household odors. For optimum performance, humidifier filter should be replaced at the beginning of each season and then every 4-6 weeks, depending on usage and hardness of water. Antimicrobial protection is infused into the growth of bacteria that can cause stains and odors or adversely affect performance. Antimicrobial Protection and Arm & hammer Baking Soda.