your pH is stable...
your temps dont go any higher then 80...
your using your nutes correctly...

hmmm

What is the ppm//tds//ec of your nutrient solution? (Starting with well water i may suspect you have a high Total dissolved salts (TDS) to begin with, what is your PPM before you add any nutes, and what is it after you add nutes?) ...for vegging plants you want to stick around 600 ppm

What do your roots look like (Healthy and white? or brown and crappy?) (if they havnt popped out of the net cups yet, how are you watering...top water or just increased the water lvl in your res?)

Did you rinse off and soak your grow rocks until the pH of the water your soaking them in does not fluctuate at all? (did you do the same to the grow cubes before use)

What is your water res temp?

...id maybe hold off on the foliar feed tell u get the problem under controll