Hello guys. For the first sorry for my english.
Thats my 3rd grow experience. I dropped one green crack and one blackberry.
I'm using
1 x 50W CFL (6400K)
1 x 100W LED
1 x 400W HPS
2 DWC systems 15l
GHE FloraGro, Micro Bloom, BioRoots, Ripen
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)