pink residue in humidifier tank

[ApplePopeye]

The bacteria you mention is not truly harmless. Take a look: http://www.antimicrobe.org/b26.asp 

Cleaning is important, and the peroxide soak with crevice scrubbing with Q-Tip should be effective.

[clownbell]

Agree with Big Guy. I use distilled white vinegar (inexpensive at the grocery store) and tap water 50-50, soak 20 minutes, and that usually does it. If more work is needed, I scrub with an old PAP machine filter, and soak another few minutes, then rinse and let it air dry.

[Phaleronic]

Follow the advice in the posts, but also please don't use an ozone cleaner.