i like having background noise so the highest fan level doesn't bother me. anyone considering this, this really is a great air purifier. it completely improved my allergies and it compltely gets rid of any smells in the air. i live in a small 1 bedroom apartment and smells from other people (smoking neighbors) waft in here all the time so this has been great for me.
Yes you can wash the pre-filter but you should avoid washing the carbon and never the hepa filter. If you wash the carbon filter it will reduce its performance. When I purchased the 5300-2 it came with 3 extra carbon filters.
The light bar shows the air quality around the purifier. If it's blue it indicates the air is good. It will change to orange, red, etc. depending on air quality. When set to auto, it will ramp up the fan speed if it detects poor air quality until it's clear, and then drop the fan speed down again once everything is blue.
