If you need to buy a hygrometer this is the one I use. Fairly cheap and can be calibrated: Hygrometer I like using an analog one because there are less parts inside that can be damaged by all the moisture. All the digital ones I have used eventually start to read wrong. The digital display will add/subtract lines to numbers (Instead of the number 3 It will look like an 8 or 9 will look like 7, for ex.)
Last edited: