The speed should correspond to the rate you would like your air cleaned. Some units have an air quality indicator light that displays your room's air quality. You can adjust your speed accordingly.
Additional Information: Particle Sensor & PM2.5
If you have a unit that does not have an air quality indicator light, you should place it at the speed that will clean your room at the fastest rate. Using it at a slower speed will take longer to clean the room.
Auto Mode Feature:
Some units are equipped with an Automatic option, which is recommended for optimal performance. In this mode, the fan speed will increase, and decrease based on the air quality detected by the unit's particle sensor.
What Does ACH Mean?
Air Changes per Hour (ACH): ACH rating indicates how many times per hour an air purifying device can exchange the air within a room. For example, an ACH rating of 5x means that the full air volume is exchanged five times every hour.
The square footage stated for an Alen Air Purifier is based on two ACH on the highest speed setting.
Why is ACH Important?
ACH is an important measurement for gauging how effective indoor air is exchanged or filtered. Regulatory bodies recommend specific ACH rates for various facilities to ensure enough air is exchanged for optimal air quality.