Product review (4 stars): Good replacement for Kenmore filters
I have relatively hard water with minerals, although not much calcium.  It takes about a month before there is a crust at the top of the filters where most of the evaporation occurs.  The filters last longer even with the crust than the original Kenmore filters do.  The advantage of the Best Air filter is that it has a metal internal support which means that when I clean them with usually just water rinsing and rubbing, they maintain their integrity better than the Kenmore.  And, even when I clean them infrequently with dilute HCL, they still retain their shape better than the Kenmore.  I can use the Best Air filters for most of the cold weather season with cleaning as above.  Then, I replace them for the next season.  They are cheaper and more practical than the Kenmore.  I run the humidifier just about all the time in the winter.  Just a fyi, I use a piece of plastic about a foot long in the humidifier to keep the floating container that holds the filters better submerged in the water.  It helps a lot.