Relative humidity

[PAPA]

Hi everyone,
Indoor grow.
4th week of 12/12 light regime.
Temp. ranges from 30 cel. max down to 19 min.
RH WAS VERY HIGH AT DARK TIME: UP TO 85%
AND A LITTLE LOW AT LIGHT HOURS: DOWN TO 35%
I ADDED A DEHUMIDIFIER AND NOW RH AT DARK IS NO
HIGHER THEN 65%.
MY QUESTION IS:
THE LIGHT HOURS RH OF 35% ON AVEREGE,
IS IT TOO LOW , CAN IT CAUSE ANY PROBLEMS??!
WHAT DO YOU THINK??!
THANK YOU.
PAPA

[Chefbjy]

Low humidity is favorable in flower. 50% is the average you would want to keep it but some prior have successfully harvested with high humidity it reduces chance of mildew mold and bud rot. 85% is really high do you have exhaust running at night? It should help keep it down along with the dehumidifier. An oscillating fan will help prevent mold and mildew too. Make sure you have good air flow. I'm sure someone might chime in about the benefit of lower humidity in flower. But I'd be worried about 85% rh 65% is okay. But try to keep it low of you can.

[Campesino]

I like the way you think!
I was typing my comment as you were posting yours...
The exhaust must be off at "night"

[Chefbjy]

Haha that was my first thought with a humidity spike like that.

[Campesino]

Are you running your exhaust fan while the lights are off?
The exhaust fan can dramatically lower humidity. It seems that with swings that large you are probably only running the exhaust while the lights are on which causes a spike in RH when the fan and lights go off. I'd suggest running the exhaust full time if you haven't been.
35% is close to perfect for mid-late flower, but 65-85 is too high.

[DW2]

Howdy PAPA, I run the exhaust and circulating fans 24/7. This helps to keep the TH at a tolerable level and with the circulating fans running as well, helps to keep the excess moisture from building up on the other leaves, reducing the probability of molds and such from getting a 'foot hold' on Your plants.