What media do you grow in? For me in coco coir more than 4 weeks in veg and I am in a jungle, 3 weeks in the RDWC is the same problem
enriched soil, but as said it's just since both my friend and me switched to LED from HPS we both observed a slower growth rate in veg with LED than with the HPS
I am sure it depends on what LED's you run but give coco coir a try if you want faster growth