The problem with running high VPD is that it taxes the plant. It is ok to drop humidity to 40 in flower, but below 40, especially during the day light hours will affect photosynthesis, especially if you are outside of VPD range .7-2.0 where stomata closes. But being on the lower end is less taxing on the plant.
When humidity is below 40 during daylight hours, photosynthesis is hindered, and furthermore if the VPD is out of range and stomata is closed, you are damaging the plants ability to optimize growth as it cannot perform photosynthesis properly when stomata is closed and the air is too dry. No transpiration happening.
The hardest part is applying the humidity to the tent without saturating the plants or a section of them.
What I’ve found is that simply reducing air exchange by reducing the amount of exhaust or air passing Through the tent and out the exhaust will definitely increase your humidity that you are inducing to the tent. At the cost of increased temps. Increased air circulation would be needed to help keep temps down. You’ll also need to spend that time messing with your setup and finding that sweet spot. But air exchange is number one reason humidity stays low. You’re intaking dry air from outside the tent. If your intake is sucking from outside the room, this is main problem. But reducing that intake air will increase humidity. So if you have an intake fan pushing air in, turn it off or all the way down. Close flaps and air leaks. Contain the humidity and reduce flow.
Cloudforfe T3 or T7 would fix your problem quickly and peg your humidity without much effort or water.
