When I first started looking for a humidifier (my wife's asthma tended to flare up in coughing fits when the humidity dropped), I realized that there seemed to be no such thing as a "perfect humidifier"! After reading through as many reviews as possible, I realized that I wanted one that needed minimal cleaning, was pretty easy to fill, wasn't too loud and did a job of raising the humidity for a fairly large area (about 1200 sq.ft) without leading to other side effects (micro dust, mold and bacteria proliferation etc.). After ruling out "warm mist humidifiers" due to the heavy cleaning needs, "ultrasonic humidifiers" due to the micro dust generation, and "in line humidifiers" due to the intensive upfront installation labor requirements, I settled on the "cool mist" HCM-300T. It promised quiet operation, cleaning needs of only once a month (the UV light is supposed to reduce 99% of bacteria growth) and the capability to humidify "medium to large" areas - as for the filling, I had come to the conclusion that no portable humidifier would help that daily chore!
The HCM-300T worked pretty well for the first 3 weeks - wife loved it since her sleep was much better, without any coughing whatsoever. However, given the absence of a built-in hygrometer, I could never figure out exactly how much of the work was being done by the HCM and how much by Mother Nature. Also, filling the water container every night turned out to be quite the juggling experience since it hasn't been designed to stand upright on its own ....in other words, you are going to have to be standing right beside it, holding it in position! On the positive side, the water seemed to stay fresh without any mold/bacteria, even though I didn't engage in any cleaning during the 3 weeks. However, during Week 4, while carrying the water container back after a refill, the lid came off (unfortunately it has been designed such that the handle of the water container is on the lid!) and the container fell down into the tub with a thud, waking up my worried wife! On further inspection, I didn't notice any leaks, so having reassured my wife that I hadn't broken any bones, I refilled the container, gingerly carrying it back to the base unit. To my dismay, when the unit was switched on, water started spraying out of the bottom of the unit through the slots that normally cool moist air flows through and soon I had water all over the carpeting. Not sure whether this was triggered by the fall, but the water leakage never stopped from then on. Needless to say I had to return the unit!!
Based on this experience, I have added three more items to my "must-have" list: a built in hygrometer (that way I can actually judge performance on those really dry days), a rugged water container (so it can outlast the tumbles that I am certain it will be taking!) and a unit that has its air outflow from the top rather than the bottom, making sure that water doesn't leak out due to gravity. Wish me luck!!