Bleached New Leaves

I disagree with others saying it is from high EC, 320 PPM is really low. She's looks stressed. Probably heat problems, root issues, the nutrient change and the PH swings. Make sure the roots are healthy, your environment is good, and your plant will be fine.

Autos start their nutrition in hydroponics their first week at 200 ppm. If their good the next week is 300, if their good the 3rd week is 400, if their good the 4th week is 500, if their good the 5th week is 600 and you stop increasing there., unless you see that their really wanting more food. Keep your water cool and your ph set at 5.8 until you see actual buds around button size, then bring your ph up to 6.2 for early bud and 6.3 for mid to late flower. Check your ph daily and adjust as necessary

Nutrient burn , the ppm is to high at this stage. Good luck with your grow

Looks like nuruturent burn from having to high ppm at such a young age or it could be root issues.