Optimum temps and humidity are for veggin: 78F temp and 60-80 RH, and for flowering: 72-75F and 30-50RH, so yes, a dehumidifier would be in order for the flowering room imo, especially if you are having mold issues. My flower room stays around 25-30%RH in the winter due to very low ambient humidity outside and I have not had any mold issues, ever.

I completely agree with GaGrown too....most people have no idea how humidity affects their comfort in their own home. It works directly with the temps to keep you comfortable! Is your house too dry in the winter when you wake up and your nose buggers are like concrete and no amount of dryer sheets gets rid of static electricity? Get a humidifier! Temp of your house is good and warm, but you feel cool and clammy, and your windows sweat up on the inside until water runs down your windowsills? Get a dehumidifier! You have to bear in mind, if you're not comfortable in your house or grow room, your plants aren't either!
TANKJR Reviewed by TANKJR on . Can you help me settle a disagreement? I started a project with a friend, and on our last outcomes we had some problems with mold and flowering times stretching weeks+ over schedule. We are running Co2 and using a 2 part fertilizer with an assortment of additives and stimulants. When in veg, they do great with good average temps., and humidity around the 70% range -- both uncontrolled except by the lights, and air intake/exaust. The room they are flowering in is located in the same environment with only a permeable membrain Rating: 5