What I see is very stretchy plants which means they are looking for light, is your light too far or not powerful enough? The stems look very weak, do you have air moving around them to strengthen them up! Pots are very small, hope you are planning on transplanting soon! 🌱👍
Hi
Fruitgrower is right you need more light and you need to transplant them they will struggle to much in those cups.
I would not add any thing in those cups no cal mag no Epsom salt till transplanted mate.
Hope this helps and good luck with your growth.