Product review (5 stars): Efficient and effective, but you need to change it more often than they say!
This type of filter works much better than the clay/aluminum based HC26E1004 pad. HOWEVER, you should be aware that this type of paper filter (the HC26P) gets moldy fairly quickly. I would recommend changing once every 2-4 weeks. The first time I used it I checked on it after only 2 months use and look at how moldy it is (see attached photo)!! Yuck! The upside of the HC26P is that it seems to humidify more efficiently (less on time and less water usage). It is definitely worth the extra price and hassle of changing the pad if you have a dry home like we do. If you want to try the HC26P I would buy at least two so you have an extra on hand if the first one gets moldy! I would check it after 2 weeks. I have mine connected to the hot water supply. I am curious to see how long others have used this filter before it gets moldy like this.