The control dial on the moist-n-aire isn't particuarly accurate - you have to use a seperate hygrometer and based on that reading, you dial the setting up or down.
I had mine set at 50% to get the cab at 65%.. I had a moist-n-aire for years.
Since my Cab was just about 7 feet tall I also had 3 separate Hydros every 2 feet.