This humidifier has a 4 gal capacity and will run 40 hours on a single filling. We purchased this humidifier for our bedroom but found it too large for that area.  It will humidify a large room up to 900 sq. ft.  We purchased a standalone unit for our living area and just leave the bedroom door open which works out fine.  I just installed a new filter at a cost of $13.00.  Here is an ad from Amazon:

Holmes Cool Mist Comfort Humidifier with Digital Control Panel, HM1865-NU
by Holmes
3.8 out of 5 stars    163 customer reviews

| 47 answered questions
Amazon'sChoicefor "holmes humidifier"
Price: $64.99 Free Shipping for Prime Members
Your cost could be $54.99. Eligible customers get a $10 bonus when reloading $100.
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Free Amazon product support included
• The 16 hour programmable timer automatically turns the humidifier on and off
• The Filter Check filter monitor indicates when a replacement filter is needed
• The large tank is easy to fill and carry and runs up to 48 hours
• 16 hour timer

I will sell the humidifier for $30.00.  Richard Fields 219 11th Ave W. Reply to email or call at (218) 387-1334

219 11th Ave W, Unit 118