This seems to keep our humidifier clean. It's really easy to use, too. Just drop it in the tank and forget about it.

Love this invention. My asthma is better since started using it, i.e. no chemicals in water tanks to be fanned in the air and inhaled. Easy, great price, reuseable. Will buy again, and again.

I don't know how they work, exactly but they DO work! I've had them in the tank for 2 winters now and they definitely help the filters stay cleaner and last longer and there is no white bulid-up on the tank EVER!

They are well worth the money--I know they look funny but believe me, they work!

We've been using these for the last two years in my dad's Vicks humidifier (that we connect to a mask that goes around his tracheostomy). Since he has an open tracheostomy, it's important to us that the moisture remains clean. So far so good - no sign of green mold in the humidifier in the years we use it. We do change the clearning cartirdige every 4-6 weeks and we protect the bulk of the humidifier from sunlight so that may be helping to prevent bacterial or fungal growth.

Last about six weeks keeping water tank clean. Does not help at all in prolonging the life of the filter.