A: These appear to be 1 1/2" thick x 7 x 9
A: Wicks need to be replaced every 4-6 weeks.
A: I just pull them out and look at them periodically. Air is drawn through them along with dust so they get dirty. Dirty filters will not allow proper air flow and the efficiency of you humidifier is less.
A: When they are visible dirty, you will know....add 7 to 10 drops of grape seed extract to your water. This will make them last an entire winter....
A: when you notice the water is lasting longer in the water container before you have to refill it, that means the filters are starting to get plugged up
A: Over time the filters absorb less water. So just look at them or feel them to see if they are wet. They tend to dry out from top to bottom. Also if they are getting mold. If you use a water treatment they won't grow mold.
A: When they get crusty and dirty. I usually change mine every 3 to 4 months. I run my 2 humidifiers 24/7.
A: Both size wicks can be used.
A: These filters are 1.5".
A: The Vornado website recommends the MD1-0034
A: The product is described correctly and accurately.
A: NO. Ultra1 Humidifiers don't use filter wicks. They are ultrasonic and use mineral cartridges. https://www.vornado.com/shop/accessories/md1-0018-mineral-cartridge