PM on flower Grand Daddy Purple

I am having trouble with Powdery mildew growing in my basement grow.
My 5x5 tent has a box fan and 3 other portable fans moving the air around. Along with carbon filter system cleaning the air coming out of the tent.
Humidity between %30 and %45.
Temps are around 73 to 75 degrees in day time and around 68 to 69 at night.
The strain is Grand Daddy Purple and they are clones from a strain bought from ILGM.
Everytime flowering starts Mildew will begin to form on the fan leaves. At this point I start picking all the leaves with PM off. I am afraid that I am defoliating too much during flower.
Foxfarm soil and Foxfarm nuts

  1. can I over defoliate in flower?
  2. best way to get rid of it?
    I have tried Neem oil solutions with peroxide, wiping them off and defoliation.

Pictures didn’t come through


I’m not a expert on mold, you don’t have hard water in humidifier?

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Problem with mold is it produces spores and it goes everywhere. It will be on the pots, walls, air, and any nook and cranny it can get took.

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Good water. Live in the city

My water is 250 in the city and was getting everywhere from humidifier on last grow, went with ro system

Not using a humidifier. My Ppm from tap is around 80

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With RH that low and fans moving air around I am surprised you are having an issue. MrPeat is correct the mildew/mold is always present so you can’t get rid of it. Good air flow usually does the trick. If it is at the soil level put a small 4" fan across it.
I run two duct fans plus a 16" fan in my hydro tent. I have two more small fans cooling my HLG light transformers. I got a bit of mildew on my hydroton, but it was covered for a while and not getting airflow. Got some air to it and it is gone. I always run RH around 60% at 78 degrees F. Even that is out of VPD range depending on chart you use. (40-70% veg, 40-50% flower, <40% final week)

Ok. I will add another duct fan to get more air flow to see if that helps. I am only running one 4" duct fan now

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