Jesus Man.
step one: fill those pots up with soil to the top, those seedlings need the earth around em, see your stem is all white and fucked.
step two: when watering wait till soil is dry, stick your finger in a good few inchs and see how wet the soil is down at the middle. when you water, take pot out, fill with your water, and wait for the excess to drain off then put in the trays, you dont want excess water in the trays cos you want air to get at the roots.
step 3: you have some ph or other lockout issue, id flush with clean ph'ed water then start on 1/4 strenght veg nutes after its dried out.
your plants look terrible for almost 8 weeks of veg, should have gone into 12/12 by now like and they should be over a foot tall at least