Looks like the plant's roots are unhappy. What are those Hydroton pellets for? You're doing organic soil, right? By how droopy the leaves look, it could be chronic overwatering. Move all those crazy pellets aside and stick your finger in the soil. Is the top inch at least dry before you water? Is your soil mix very heavy? What percentage of perlite did you add?
If you're truly doing an organic grow, over doing nutrients or getting lockout due to pH issues shouldn't be an issue. But I'd double check anyway. Just remember the soil mix additives are not there to feed your plants. They're added to feed your bacteria and fungi. And you need to check your conditions for optimal growth of those creatures - not your plants. Are you feeding them during growth, or are you using the seedling to harvest without any additives?