How do I reset the "Filter" light on my air purifier?

Once the filter has been changed, you need to tell the air purifier that it has a new filter and reset its countdown to zero. The easiest way to do this is to refer to the user manual. In most cases, you need to press the "filter" button or a button near the "filter" light for about ten seconds.

On some older Blueair purifiers, there is a hidden button under the control panel. You can tell because it has a slight bump on it, which you can also feel when you touch it. Blueair Pro purifiers also have a hidden button that is located below the "Filter" indicator. It must be pressed for 3 seconds.