Just thought I'd drop this Nug (hehe). I too have had an
impossible time keeping RH up with my 440cfm 6 inch inline extraction fan going, even with two humidifiers! The only way I have been able to keep a stable and suitable RH environment (probably temp too) was to keep the fan off most of the time.
What I have done is add a digital timer on the fan so that it goes on 2 times every 35 minutes for 2 minutes each time. This should be (for now) enough exhaust out and pulling in some fresh C02 while my 3 plants are at this young, fragile stage. I also have 2x 6 inch clip-on fans and another 10 inch pulling in near the bottom (passive) intake area of my 3x3 tent for good air movement.
Now once they start getting a little beefier/stronger and they are spitting out lots of oxygen and that fine but all powerful smell the fan will need to be on a lot more (probably 24/7), but by that point they should be able to handle a bit lower humidity and still manage (I hope!).
Hope this helps! Keep the green thumbs strong
@SirGreen @Colderia
SG--
-- AND it's the low RH that's causing this mostly, I see signs of it already in those up-turned edges (same as usual with your grow, right?
).... the plant is taking in more water to deal with the high transpiration rates, and along with it, nutrients! Plants take up several nutes whether they need them or not, and N is top of that list, so it's likely that a few of these are just getting overloaded because of the environmental issues,... get a small humidifier, maybe hang a wet hand towel in there, anything to get the RH over 40%,... and reduce feed conc. on them meantime,...
) my RH was about %14-%20 i bought a humidifier its now %50-%65 and solved many of my problems BTW that thanks goes to 
