The frequency with which a media air cleaner should be changed is determined by factors such as the type of filter, the quality of air in your home, and the manufacturer's recommendations. Media air filters should be replaced every 6 to 12 months on average. If you have pets, allergies, or live in a polluted region, you may need to replace the filter more frequently, such as every 3 to 6 months. Regularly inspecting the filter and adhering to the manufacturer's standards or the recommendations of HVAC professionals will assist you in determining the best replacement plan for your specific situation.