Soehle Air Fresh Clean 400 Dehumidifier Air Purifier 3 stage replacement filter. This high-quality filter has a pre-filter, a HEPA filter and an activated carbon filter. This superior 3 stage filter removes 99.95% of all allergens and pollutants up to a size of 3 µm from the air in an around your home, office or work space. Soehnle recommend regularly replacing the activated carbon filter to ensure your Air Clean Purifier continues to consistently operate at maintaining a high level of cleaning performance.