this may sound like a noob or ghetto idea... but... fill a bottle of water leave the top off in the room. my humidity % was perfect untill i left a bottle of water on the self next morning my %'s where way high.
Put you fan on any time, when they are small have the fan air hit a wall then that lets the air turn, you can have the fan pointing at your plants when they are bigger and can handle it, a light breeze is perfect.