Leemone Humidifier Cleaner 20 Pack ，Demineralization Cleaning Ball，Works in All humidifiers and Fish Tanks，Purifies Water, Prevents Hard Water Build-Up，Eliminates White Dust and Odor

These work in ultrasonic cool mist humidifiers to reduce the "white dust" from hard water. These have worked well for us. Keep in mind that we do do not have a water softener system, and we not have a lot of mineral content in our well water, so your results might be different. That said, when we first tried ultrasonic humidifiers we noticed a significant amount of white dust after a couple of week's use despite our relatively soft water. We saw these on Amazon and gave them a try. The reduced the dust problem significantly. We use 6-8 beads in each humidifier, more than the instructions specify, but the results have been excellent. With 3 humidifiers running 24/7 in a 1300sf area we have no problems with dust. Again, your results will vary depending on the hardness of your water, but these have worked well for us.

I'm giving 3 stars because they are cute, the downside is I'm still seeing buildup inside my humidifiers daily. May try a different product. I fill them fresh daily and trying to avoid buying a ton of DI water.

They are working quite well. Usually I have to descale the humidifier after every other fill but it’s still going with no sediment! Those fishies are floating like champs.

I don't think it works. I have a TDS meter and it's showing 300 PPM for the water in the humidifier. I have 4 capsules sitting in there for at least 8 hours. Normally my tap water gives 150 ppm on the tds meter.

I bought these for two reasons: anti-biocontaminant and the claim it will de-mineralize water. These balls are silver impregnated... and that is the ONLY active ingredient. Silver will not demineralize water. It will not eliminate or even reduce "white dust"... which is calcium that comes from the water itself. As an anti-bio device it's fine; silver is well-known for killing unwanted bacteria. But advertising it as a demineralization device is hogwash. Regarding how long they last: some people report they last a year. That seems more far-fetched imagination than reality. Others say they last a month. That's fine; if it lasts a month this box contains enough to last at least a year. As a bacteriostat, that's acceptable. I rate this one star for questionable advertising claims. Demineralization? Hardly. You'll still wind up with white dust all over the place.