Big Devil Auto

So the first full week since germinated and putting into final pots has gone by. The stems are looking very weak and thin and one plant actually toppled over. I ended up adding more soil around it to support it better. Not sure what this is due to? I have only been giving plants tap water around 6.8 PH and only when dry up to first knuckle.. which I check normally once in morning and at night. Light schedule is 19/5. Will be changing to 18/6 once my new lights come in. Been running a 19W led strip about 10-12” away from pots. Good airflow to help strengthen stems and not sure what is going on with the leaves discoloring and whatnot. Any tips or advice as to what’s going on??