no one has asked the OP to provide more info. you can't just put up a couple pics and the question "what's wrong?" and get a decent answer. more info is needed.
one mistake was to put that many plants into such a small space. another mistake was using such a small fan. that homemade box isn't good, not to mention the dirtiness. unpleasant to look at and bad to grow in as plants will get bigger (provided you do it right). The OP could do this: use Dynagrow fert, one teaspoon per gallon in hydro, and see what happens. This is when you don't want to buy a ppm gizmo. Maybe the best thing would be to just switch to soil as there is a smaller margin of error, but soil always takes longer.