What is this chalky look in the leaves?

All hydro, 2 x 6 closet, 600w of flouresc tubes from all directions, 80 degrees constant, solid air flow.

I'm in the 3rd week of flower with the same nutes I've been running for 2 months. All looked great until last few days, now I'm getting a slight chalky look to most previously lush green growth. It's in the leaf itself, and not something on the leaf.

Also, a few leaves on each plant are sponteneously turning black and dying one at a time. Not like a slow browning of a leaf...they turn straight black in about a day or two and die off.

Am I over feeding? It's General Hydo 2200 ppm or so. I was doing 3000ppm and actually back it off when I started flower. Been kicking ass until now.

Anyone got ideas??

ph fluctuation?

Hard to see really good on those pics but I'd guess maybe powdery mildew. I haven't had the issue with my plants, but have had it on zucchini leaves before

Definately not mildew or anything on the leaves. The color change is in the leaf itself.

I started using H2O2 a couple weeks back and I noticed it turned my brand new fresh nute water from the usual tea color to crystal clear. I'm using 29% at about 7ml per gallon twice a week. Could that be it?

You might be bleaching out the leaves with the H202, this is only a speculation tho

anything over 10% pure h202 is a weed killer