When the filter is discolored, replace it with a new one. The procedure is as follows.1. Remove the filter by pulling the filter cover out and then removing it.2. Use a sharp tool such as a toothpick to remove the filter. Discard the removed filter and replace it with a new one.3. Install the filter cover.Note:Use only filters that are specific to this product. Do not use this product without a filter attached.The filter is not divided into front and back.Make sure the filter is clean and free of dust before replacement.Do not clean the filter. If the filter is wet, replace the filter. The filter will cause blockage when it gets wet.To prevent clogging of the filter cover, clean the filter cover regularly. Do not boil the filter cover. When cleaning, be sure to remove the filter cover first. Dry thoroughly after washing and install the filter cover in the correct way.