Pure Guardian H910BL Ultrasonic Cool Mist Humidifier, 14 Hrs. Run Time, 210 Sq. Ft. Coverage, Small Rooms, Quiet, Filter Free

"5.0 out of 5 stars" - I bought this to use for an elderly cat who had recently been suffering from allergies, which was causing a condition known as reverse sneezing & also some asthma attacks. My vet had recommended getting a vaporizer or humidifier to use where he sleeps to alleviate his symptoms and lung irritation. I had a humidifier & that helped, but it is a warm steam variety (not good in the heat of summer when the a/c is blasting in other rooms) and automatically shuts-off once the max humidity is reached (so it won't run continuously).I found this little cool mist vaporizer & have been very pleased with it. It was much smaller than I had thought it would be, even after reading other reviews & seeing the pictures. But it is sufficient & puts out a nice, constant stream of cool mist until the tank empties. It has about a 6' cord, which I wish was a little longer, but I guess that's what extension cords were invented for! It works virtually silently as well, which is nice so it doesn't disturb the cat (& also would be great for a nursery as well). I use refrigerated distilled water & haven't noticed any kind of build-up at all, or any white powdery residue. I have it on a tile floor, and while the floor around it does feel cooler to the touch, there is no moisture from the unit accumulating that I have noticed.The very top can be twisted to direct the mist flow. The on/off button has a small, unobtrusive backlight - blue when it is on & red when the tank needs to be re-filled. That one button is the one that cycles through the 4 combo modes. The blue nightlight feature lights up inside the water tank itself. It can be used when it is in either the low or high mist flow setting. I guess some people think it may be too bright, but I didn't find it any brighter than any other nightlight I've ever used.I think it only holds a little less than a quart of water at a time (per the manual, precisely .21 gallons), and on the low setting found it would run for about 10-12 hours I think, so enough to run through the night. The tank itself will be hard to clean - the opening is fairly small & the manufacturer recommends a bottle brush. The tank does have some coating to help resist build-up in the interior. There is a tiny brush snapped into the base, to be used to gently clean the ultrasonic disk. The only other recommended method of cleaning that part of the base is with a small amount of vinegar/water solution to help remove any build-up from the disk (without scraping or scrubbing it, which will damage it).So far it has worked great for its intended purpose. My cat's breathing has definitely improved (asthma attacks stopped!) & this is better than using the warm steam humidifier in the summer months. I'll switch back to that in the fall/winter. Hopefully this will stand up to daily use in the meantime - will update review if there turn out to be any problems later.

"3.0 out of 5 stars" - Nice product but it is definitely too small. I borrowed the same unit but bigger and it works really well. So spend the little bit more money and get the bigger one. It lasts a lot longer and easier to not have to fill it up so often.