Product review (5 stars): I try products like this with the intention that they will not work
These little guys seriously work, and I mean they work very well! Being from an area with some of the hardest water in the country, I try products like this with the intention that they will not work. I was pleasantly surprised to see the hard water buildup reduced by about 70%-80%, based on how bad our humidifier collects lime and hard water buildup on all of the exposed parts. Though I can't say for sure how long they last, as I have only had them a few days, with how well they work, I'll replace them monthly if I have to, knowing how well they work and how cleanup is much easier while they are still active!