Product review (3 stars): Here's how to clean them...
I bought the Kenmore humidifier at the beginning of winter. We have hard water in my area, so it gets nasty far too quickly. I'm on my second of the season. As the other reviewers have noted, it tears/shreds and loses form far too easily. But I have figured out a way to prolong the life of the filters a least once or twice. I cannot use the bacteriostatic fluid. Tried it - it gave me breathing problems. Maybe I can find another type. If you aren't sensitive to the bacteriostatic liquid I strongly suggest you use it. It really does prolong the life of the filter. These filters degrade very quickly. A new filter makes allows the humidifier to work very well, but within a few weeks, the humidifier starts having trouble reaching the same levels of humidity, and more and more water is required, i.e. it becomes far less efficient.

To clean this filter: Remove the filter while it is somewhat dry (to avoid ripping/shredding). Here's the key: DO NOT wash it! *SOAK* it instead in a water bucket filled with vinegar and hot water. After a little while, GENTLY pour out most of the water WITHOUT touching the filter. Refill w/ hot water and a bit more vinegar. Second most important thing: do NOT lift the wet filter after soaking it! You will tear it. Let it dry in the bucket before attempting to pull it out. Last, if the form is too far gone and the circle can't be "closed", I just use two small safety pins (near the top and bottom) to close the gap. I am able to clean them twice before needing to use a new one. It's better than putting in a new filter every 3 weeks! Here in Canada, they are $20 each!