You mentioned light burn. I don't think so. Light burn would be on the leaves closest to the light, and it's not oriented towards the tips. Tip curling is overwatering or nute burn. I see general nute burn, and what looks like mites to me. Could be thrips, but looks more like mites to me. Thrip damage is larger spots, and they are irregular, not round. Either way,
Azamax or
spinosad, used as directed, will clear that up. Three or four treatments, 3 or four days apart. Both are safe for humans and beneficial insects.
I don't fuck around with exotic organic soil mixes for this reason. There is no way to tell what you are out of balance on. Nor is there an easy, natural/organic/hippyfuckingdippy way to fix it. You should check your pH, and correct it if needed, in case you're locking out. Thats a pretty common problem. But then you'll be confronted with using either lime or sulpher compounds, not organic/hippyfuckingdippy. Frankly, I don't have a lot of patience with failed organic grows. You want to follow a religion, more power to you, but its not the easiest way to grow weed.
Personally, I make a neutral, balanced, well draining soil, spike it with cow manure compost every spring, and use
Botanicare veg and bloom at 3/4 strength. Check out the top and bottom links in my sig for an indication of how that works. You have to be pretty good at organics to equal my lazy man's semi organic yield and quality.