Filters should be changed regularly to ensure good air quality. In addition, dirty filters are the #1 cause of furnace failure. Change your 4” pleated filter every 90 days to ensure you maintain a healthy home and a healthy family. Better yet, take the guesswork out of it and join our Annual Filter Replacement Program! Automatically receive a new filter at your door every 90 days as a reminder to change your filter. Seems to work well reviewed on Oct 13, 2014 really makes a difference reviewed on Jul 12, 2013 ergonomic, silent operation, portable easy to assemble, semi commercial use possible (e.g. waiting area, small cafe/restaurants etc) why has this product not been given the proper advertising it truly deserves? Daikin Air Purifier Model MC707PVM reviewed on Apr 11, 2013 Easy to Set-Up and Use. Easy to install filters. Looks great as well. Doesn't have a "Night Mode" button on the remote as suggested in its advertising. Dues this model need to stand on something or can I stand it on the floor so long as there is lots of room all around