Product review (5 stars): I've read the reviews that say "just buy the pre-loaded ...
I've read the reviews that say "just buy the pre-loaded cartridge because it is impossible to load these yourself" and just SMH.  Every once and a while water won't flow freely through one of the two vaporizers I have going in winter months.  I reload the cartridge using the styrofoam plug and fill cup, screw the lid back on, soak it for 24 hours and am back in business.  I get no white dust [I fill the reservoir with hot water to give the water softener a crack at keeping the minerals down] and have zero issues.  I do agree that this product may now be made by a different company than the one I first used 4 years ago, but it still works.