I live in desert conditions and what I do is run this large humidifier from Sears
http://www.sears.ca/product/kenmore-...-758_3_299740C
And control it with a humidistat from Charley's Greenhouse supply.
http://www.charleysgreenhouse.com/in...2=-99&cid3=-99
I keep my snake room at around 45% humidity and inside the tubs its about 10% higher.