Hey there, i have to disagree with the folks on this one. the curling is indicative or root problems probably cause from not follow a strict wet dry cycle. As previously said, you should wait until you have a decent tap root poking out before placing in the DWC, but what i'm most concerned about is the discoloration on the outside edge of the cotelydon and first leaf, this is a symptom of magnesium deficiency, which i guess is a lockout in your case. My best advice is start over as these plants might be stunted , next time, as long as it's in the root cube, just water with plain water, and if you really want to give food to the babies, try spraying twice a week with kelp extract rather than watering with feed at this early stage (you can add your cal mag in the foliar spray too). The uptake through the leaves is much more efficient first of all, and at the seedling stage there's more leaf that root so it really helps on the spray. Sorry about the bad news, but it's my level best lol Hope this helps ! 🚀