Purple/red stems in veg/4 weeks old

Usually red stem means plant git a little close to light at some point. Think sunburn. It should be fine.

Hi there,To me, Everthing seems to be fined.Nothing to worry about.Since you are growing in soil, the less nutrient the better.Also give water only when your top soil is dried about an inch to two and keep run off around 10~15% to prevent salt build up.Check both of your water pH, ppm(EC) and run off.You don’t need to water everyday and you don’t need to feed everytime you water.Always listen to your plants.Happy Growing... ✌️