Have you only checked it with one humidity divice? Maybe you have a bad one. Maybe something to check.
bigworm1922 Reviewed by bigworm1922 on . PLEASE HELP...im ready to pull my hair out! HUMIDITY... I am not sure why I am having such a big problem with keeping ANY humidity in my grow box. I just completely re-built it and still no humidity. Here is what I have: 1) 4' wide x 2' deep x 5' tall box in garage 2) lined with panda paper 3) 400W HPS approx. 18" from canopy...glass on hood soon to come! 4) 6 plants vegging in 12 inch round 3 gallon pots filled with FF soil 5) 2 speed circulating fan in box... 6) active 8" exhaust out the top of box...restricted massively 7) 2 4" holes on Rating: 5