Here's an example of a good use for the 67:
Right now I've got my tent in 'drying' mode...stems hanging, lights out and I have a humidifier in the tent as well, but it's not really triggering (set to 65% but only 'in case of'.
I have my temp triggers on the 67 turned off and I have the high humidity trigger set at 63% for drying. I've got my 'transitions' and fan set up like this:
"Off Speed" set for 3. That means when the fans aren't triggered at all by temperature or humidity (highs or lows), in 'resting mode' the fans are running at speed 3. It means that at the very least the fans will always be on and push/pulling air through the tent.
"On Speed" is set for 7. This means that when a trigger happens (high temp, high humidity, lows, etc.) the fans starts to increase their speeds, but can only go as high as 7 out of 10.
Transitions for temperature are set for 2f degree increments. This mean if a high temp trigger trips the fan goes faster. If it's set for 76 it means that at 76-77 the fan speed ramps up one notch to 4. If it hits 78-79 it goes up to 5 and so on until it reaches speed 7, the 'on' setting.
Transitions for humidity are set for 1% increments and it acts similarly with increases in humidity.
I have mine set at 63% for drying and it's keeping the tent between 62-64%...without a humidifier. My damp soil in bags is still in the tent and releasing moisture into the air. The fans are pulling in dry air to balance the moisture being released.
The learning curve is finding the balancing point for the situation. So you set your temp trigger a little lower than your ideal, etc. then the controller finds a place where it keeps the environment just where you want it...it applies a bit of fan when things try to deviate and if they deviate more it gives more fan to bring it back down.