From our friends at Crane USA
Uses for humidifiers range from preventing dry skin in the winter to relieving allergies to keeping wood furniture from cracking. No matter what you’re using it for, cleaning your humidifier regularly helps the machine run properly and prevents buildup of minerals and bacteria. Each day, be sure to dump out excess water from the humidifier, and clean the entire unit about once per week.
A few tablespoons of vinegar and a few cups of water can go a long way in the maintenance of your humidifier. Simply add two tablespoons of vinegar (feel free to estimate this measurement) and two cups of water to the tank and shake to distribute the solution. Then dump it out. Add the same amount of vinegar and water to the base and let sit for 20-30 minutes and scrub in any tight areas with a Q-Tip. Then dump it out. Be sure to rinse the tank and base when you’ve finished!
Still have trouble removing buildup? To help scrub the inside of the tank, try using a baby bottle brush, which are usually wire and able to bend into the hard to reach places of the tank. You can also use crushed ice. Add a few cups of crushed ice cubes into the tank with a cup of water. This won’t scratch the tank, and the ice cubes will act as scrubbers, removing any buildup from the inside of your tank.