Okay, what i think it is, is because of stress, and to little light, and as i said before idk bout LEDs, only HID and CFL cuz thats what ive been growing.
Think about the temp and humidity, you have to have those dialed in. And also i thin vegs like alil more moisture than flowering, so i suggest that you dont let them dry out too much. And are you checking ph of the soil?
About the blotch, i cant tell because of the lights, try a normal light instead of under ur LEDs.
peace!
edit: You gave them water thats PH 5. Thats way to low. Mostly my soil has been lower than the water i put in, and i put in 7phd water(normal tap water)