Just wanted to thank Roo. I read your prior article about Humidifier setups and tried it myself. I used the Holmes 2.8 Gl. ultrasonic as suggested and it works great. I run it 3 times a day for 2 hours at a time. I give 2 hours in between for drying out. I tbrought my humidity levels up from about 40% to 54%. Thats a pretty good jump, but I was wondering if that was a good target level? I live in San Diego and right now it is pretty dry. Can anyone help me out?