Edges of new growth

Too much nitrogen, not enough magnesium. Not a lighting issue. Since you are growing in a coco mix, you will need to add cal/mag from virtually day one.

First of all, you should reduce your grow fertilizer. Leaves accumulated in nitrogen are also exhausted due to magnesium deficiency. You may be experiencing a pH problem or nutrient lockout. I recommend that you measure the pH and ppm of the water flowing from the bottom when you water.

Magnesium deficiency usually starts at the lower leaves. It is a mobile nutrient and the cannabis plant is able to move it's stored magnesium from its older growth to the newer growth. So you typically won't see it begin to develop in newer growth. I would say this is likely an uptake issue caused by a nutrient/ pH clash.

What I see is a build up of nutrition in the medium. As you are not getting enough run off when you feed. The salts are accumulated and your experiencing nitrogen toxicity, and the ph has probably dropped a lot. What Is your run off ph, and tds?

The way the leaf looks in the second picture with the light green streaking and a burnt tip it’s looking like the very early start to magnesium deficiency. You can mix up a foiler spray with Magnesium Chloride for quick absorption. If you are experiencing a lockout, foiler spray bypasses the roots. I tsp per gallon and spray right before lights go off. Hope this helps.

You need to check the PH of your water/nutrient solution, this is a deficiency of nutrients... usually caused by incorrect PH.. not a lack of nutrient. PH 6.3 is the minimum for soil.