First Grow - Organic ChemPie

1/20 - Finally recovered from the transplant. Took almost 2 weeks to recover. Had steady growth for the past 4 days. Still spritzing to water these even in the 7 gallon grow pots. Watering every other day, and giving nutes every other watering. 1/26 - White stuff on a few leaves. I used tap water for the humidifier and the tap water is very hard. I assumed it was build up from the vapor. I'm starting to wonder if it's actually white powdery mildew cause from the vapors. Grow question below.