There are a few different types of humidifier filters that are available on the market. The most common type is a fiberglass filter. This filter is effective at trapping dust and other particles from the air. However, it does not treat water well, so it is not recommended for use in humidifiers that have a tank.Another common type of humidifier filter is the activated carbon filter. This type of filter is effective at removing unpleasant smells and chemicals from the air. It also helps to prevent the growth of mold and bacteria in the water tank.A third type of humidifier filter is the electronic filter. This type of filter uses a fan to blow air through it, which helps to remove large particles from the air. It also has an activated carbon section to remove bad smells and chemicals from the air.