ProTec PC-2 Humidifier Tank Cleaning Cartridge, 2-Count Packages (1 pack of 2 cartridges)

These little doohickeys actually last a lot longer than the manufacturer states. We kept one in both of our humidifiers for years and never had any indication of mold or mildew. There are others that look like these things, but you need the ones that are made with silver. We only replaced ours because we replaced our humidifiers after more than a decade of use. I can't say yours will last that long, nor can I recommend you never change them. I can say they work great.

This was one of the best investments I ever made. I bought a new humidifier, a Honeywell with outstanding reviews, and the filter gave me trouble. In a little over a week it smelled mouldy in a really foul way, and within 2 weeks the filter literally fell to pieces in my hands. These are expensive filters to last such a short time. I changed the filter and bought 2 ProTec balls, one for each tank. It worked like magic! No smell, no moldy discoloration. These things are wonderful! If you're sitting on the fence, jump off it! Run and buy one of these things right now!

I've been using these for a couple of weeks and they seem to work well as intended - which is to extend the amount of time in between humidifier cleanings. I've noticed that the slimy film I would notice on the lid doesn't even start appearing for a couple of weeks - which is a week or more longer than without. I think some of the bad reviews are from people who wrongly believe they never need to clean their humidifier or who think they don't have to do it very often. Wrong. You still need to clean the humidifier. This just lets you go a little longer in between cleanings.

Works great, keeps humidifier bacteria free.

I thought when you use this thing, you don't need to clean as often, but I found that there are orange water stain and some black stains building up after a couple of weeks. I would rather use bleach and vinegar to do cleaning and s disinfecting weekly. I will not buy again.