Powdery Mildew Problem in Hydro System

had a lot of success in soil, but yesterday i went to check my hydro system, about 3 weeks from harvest, fucking mildew spots on some of the leaves. what can i do? i have some neem oil that im thinking of spraying. i dont see any mildew on the buds. i put a dehumidifier in the flower room. my temps are about 80-83F. i fucked up big time when i set the grow room up a couple months ago. the basement had a little mildew, and even though my friend and i cleaned and painted, we should have sealed the area. now i think i have to move the whole operation cause i think its just a bad place to grow and dont want to risk this again. i also turned up the circulation fans. anything else i can do? it didnt spread to other plants yet, just the 2 in the hydro system but im risking losing between a 4-8 ounces which is what is paying for my equipment and such. also i change my hydro res every week. using botanicare pure blend pro nutrients, the whole fucking line and suppliments except zho. cost me about $200 just for that. in flower i only use hps. thanks

anyone? pretty please? i sprayed my plants down last night with this 3 in one stuff. it has some kind of oil in it and sulfur. claims safe up to the day of harvest.

another question i have is, when im drying the plant, how to i be sure it wont come back?

Oh man, that's rough. All i can suggest is good ventilation. Are you getting fresh air in there? or is the air at least moving around? Keep in mind, you can check for mold with a black light.

I tried "PM wash" on my DWC and all it did was spread the mildew all over the fucking place. There is an industrial product that grape growers use for PM called AQ-10.. I can't find it for sale though. Any thoughts?