Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Hunter 30756 PermaLife Tower Air Purifier with 3-Speed Fan

1) Tower air purifier is somewhat noisy on its fast setting and a distraction on the "Turbo" setting.2) Would like to be able to purchase an extra cleanable hepa filter but Hunter makes it difficult to buy. Their website and the productmanual which comes with the unit doesn't even mention the possiblity of buying an extra in case the supplied "lifetime" one is accidently damaged during cleaning or handling.3) The automatic guage which tells you when to replace the prefilter and the when to clean the main hepa filter works on the accumulated time the unit has been running since the last replacement or cleaning. This may cause you to be late in doing maintaince on the filters if the unit is filtering air that has more particulates per unit/volume than what the air quality engineers designed the unit to treat.