Product review (5 stars): Will never use a different filter.
I have been using these filters from Amazon now for three seasons. They are as good as the one that came with the humidifier, and have never had a problem with them. I have very hard water, so I add Holmes Humidifier Water Treatment to help prolong the life of the wicking filter. One filter will last me a whole season ( I do flip the filter ever other fill). I also add a Bacteriostatic to the water to help stop bacteria and algae build-up. I get great humidification all season long, even though I live very far north, where winters are long and very cold.