To my understanding the guano is broken down by microbes in the soil which is then turned into something your plants can use. So i cant see a humidifier doing anything good other than putting bat/bird shit into the air (i would bet the filter wouldn't allow it to take any of the guano up), and if you're breathing the guano in then its probably doing more harm then good. You may of cut down on your nutes/more nutes, better PH'ed water allowing less lockup, and the millions of other things that it could be. I just dont see adding shit to a humidifier doing any good because to my understanding thats now how plants work.