Product review (4 stars): Worked fine
Surprised at how long this extended the life of my humidifier filters. Lasted maybe 6-7 weeks instead of 3-4. That's great during the winter months when filters for my humidifier cost $20... but during the summer months the filters sell for less than half that. I'd rather just stock up on the discounted filters instead of buying this stuff for more than the cost of a filter. I had to use most of the bottle in that 6-7 week time period.