Review on FLT4825 HEPA Filter B: Compatible with GermGuardian AC4825 / AC4825E / AC4825DLX, AC4300BPTCA / AC4850PT - Advanced Technologies for Home Air Cleaner Purifiers, AC4900CA, CDAP4500BCA by Rick Pickering

I didn't realize how much dirt and dust had accumulated on the filter. When the red light started flashing, it meant the filter needed to be replaced. It wasn't difficult to figure out which filter you need, since everything is written on the machine itself. As soon as I received the filter (with very fast service), I opened the car and there was a dirty filter. It was very easy to take it out and put a new one in. What I didn't know was to hold the UV light for 5 seconds to reset the filter's flashing light. Thanks to your email survey, you reminded me of this. The machine is now running at optimal performance. Thank you! I will be replacing my filter in 6-9 months as directed. Thank you for a good product at a reasonable price.