How do you treat your humidifier?

[JoseKnows]

When I used a "just refill-distilled" routine, there was eventually some red (algal?  bacterial?) growth.   
I now empty each morning and dry with a bit of tissue and set it aside to dry thoroughly.  No problems and perfectly clean for YEARS.

[GuyScharf]

Reverse osmosis water. Top off nightly (I use about 3/4 of tank in a typical night). Empty and rinse every few days. Wash occasionally.

[Snooks]

Can it hurt the machine if the humidifier water tank run dry?

[Deborah K.]

It does not harm anything if the tank runs dry.  

I used to use distilled water, but was tired of carrying it up the stairs all the time.  Now I use regular tap water that is very hard water.  I was cleaning it out with vinegar, but it did leave a smell, so I switched to a heaping teaspoon of citric acid powder dissolved in warm water, and let it sit for about half an hour.  Then it rubbed a little with an old toothbrush, and it came clean way easier than it had with the vinegar.  I've never seen anything slimy or a funny color, just the white build up from my hard water.

It makes no difference what kind of water you use, you are just breathing in the mist created by the humidifier.  It will always be perfectly clean, and will not transport any chemicals from hard water or from any other kind of water.

[RayBee]

Distilled water only.
Pour in just over halfway to full line.
Use almost all of it over night.
Pour unused water back into the gallon jug in the morning.
Shake out the tank and leave it open to air dry. Set silicone gasket aside to air dry.

A gallon jug lasts about three to four weeks.

Tank and silicone seal still look like new.