Yellowing leaves turn crispy

View attachment 1644616 View attachment 1644616 I'm 6 weeks into my first grow and I have tried everything I can think of and researched but I can't get my leaves to stop turning yellow. I thought it was nitrogen deficiency because the yellowing starts at the bottom and progresses up. I bought the fox farms trio and have been following the table but halving the amounts. I thought they were good but it started again so I thought maybe it was nutrient burn so I fourthed the nutrients but now I'm back to thinking it's a deficiency or over watering. I water only when the top few inches are dry and the leaves just start to droop. 
Things to consider:
4x4 grow tent
MARS II 1000 watt LED grow light. 
Batch 64 soil 
PH water to 6.5
PH in root zone is ~6.5
Tent is in my room so I close all of the draw string holes and the mesh vents at the bottom when I sleep
Fan inside (not directly blowing on plants)
Smart pots
Has been happening to all 4 plants the entire grow
My thoughts:
The only things I can think of are over/under watering, nutrient burn/deficiency, or the batch 64 moonshine soil. Next time I will go with roots organic + perlite. 
 
I would immensely appreciate any thoughts or suggestions so I can figure this out once and for all. 
 
This is what is in the soil: (coconut coir, perlite, pumice, rice hulls, expanded shale, humus, worm castings, biochar, feather meal, fishbone meal, blood meal, alfalfa meal, oyster shell, metamorphosed evaporite, flax seed meal, cotton seed meal, dried molasses, kelp meal, azomite, potassium sulfate, limestone, yucca extract, and mycorrhizae.)

 

Thank you a ton! I will even out the amount of nutrients at a time.