First time Indoor Grow

OK guys here we go week 1 I'm seeing a definite deficiency here in Punch 2 with the purple stem. Punch 1 seems to be fine, maybe a bit droopy. Zkittlez didn't make it I suspected it was too cold for her, but I think it could have been mold. I have added a fan on the floor of the tent (the pots are raised about 25cm off the floor so the roots don't get too cold). The light has been adjusted to 30cm again as they grew a few cm and I have turned it up to 90%. I didn't add anything other than the old root system of the last plants and I am thinking the one with the purple stem has a mag/phosphorus deficiency and I have no idea how to treat it in little babies😭 Help guys any advice should I add organic waste to water to add them of leave them be a few weeks? 🙏