Day 24 - put Green Crack into DWC 15l.
Day 27 - looks much better and healthy.
Day 28 - Roots looks healthy. 8cm, Ph 5,8, ppm 300. Finally Vegetation. Added little nutrients.
My mistake were - too high ph, added nutrients too early.
What types of lights are you using? Your plants are very small for 4 weeks old and have stretched a lot. Are you checking the PH of your water ? It looks like the leaves are yellowing from either lack of nutrients or wrong PH.
I’m still learning myself. Look at my diary for similar 4 weeks age (under week 5)