Product review (5 stars): Good filters
This was a great price for a 6-pack of these filters.  They are necessary for the humidifier, but they do have a short life span.  It's just part of the reality for them.  We use only filtered water to fill the tank, open the top and leave it open to the air during the day, and try to clean out the unit reasonably regularly.  This lengthens the lifespan, but unfortunately you just have to get used to them needing to be replaced.