hi all,im in the process of a growing come back after some years out and am having a go at hydro again and making my own system was thinking along the lines of the wilma but wana grow some trees and there pots are small so was thinking of like a wilma setup but with 20L pots but am gonna get a bigger resivour 100L + but didnt wanna put it in the growroom due to the fact that the water will evaporate wont it and bring humidity up?so was just wondering if this is true or not and if so how much rise we talking??

with good venting in your grow room/grow box, you should be fine. remember you can also put your resivour outside of the grow box/grow room. That can reduce the humidity it'll produce. in early stages you can let the humidity build with that and when your ready pump out some air and it'll drop it. This is also depending on the relative humidity outside. if that's high to start. you can always invest in a de-humidifier.