Having bought a Filtrete Air Purifier this past July, I was wondering how long it would be before I got the flashing red light to tell me I needed to change my filter and around Christmas time was that time - so the longevity for one of these filters is around 5 months.
First thing to notice when comparing the used and the new is how white the new is compared to the dusty grey and blacks of the used, showing how effective the air purifier is and how much dirt and grime there is in the air, living in the city (and in my flat, I suppose).
It's easy to swap out, removing the back panel of the purifier, slipping out the old filter but, for first time users like me, before you put in the new filter, hold down the red button so that the purifier knows that the filter has been changed, and then put in the new filter.
Voila, start it up and you get the green light to tell you everything's ready to go once again! Great value for a great product, I recommend the air purifier to anyone with breathing problems like asthma to help them breathe easier in the homes, especially at night.