What level of humidity should I keep my bloom/flowering room at?

You want to keep the humidity in your blooming/flowering room around 40%-60%. Keeping the humidity below 40% will cause your plants too dry out & the water could evaporate to fast. Having a humidity above 60% will cause your plants to be more susceptible to rot root & other root bound diseases. Having the humidity too high might also cause your plants to get moldy.