390cfm 6" inline fan, how do you keep the humidity at a proper % the most I get is 49%

I am using a Vivosun 5X5 tent

4 plants

4 different strains

5 gallon bags

Advanced Nutrients

Pro Mix medium

I run the exhaust to keep the smells out with a charcoal filter

I would like to grow 6 plants at a time but would see an issue with watering with a trellis net installed