I hate that stuff. It is the reason I went back to Cubes! I get roots easily in a Week strain and parameters withstanding. Some versions of it will not even bleach out. However, since the Dewey Mister is less hidden moving parts you should be able to disinfect! I would soak the Mister itself in more than 10%. I would even ask the company (type of plastic) and boil that thing if the plastic was withstand the heat....
BTW do a search for Cyano Bacteria SLime Clones or something I forgot what it has been identified as. I ran how water bleach solution through a small EzClone and that shit survived! Some say it lives in the Pump.... Aero Cloning is way more trouble for less results IMHO. Root Riot/Dip-n-Grow heat mat 80 Degree/ dome = guaranteed roots very fast...