What's wrong... Nute burn? light stress? tips...

Gottagro has never taken a real chemistry class, i promise you that based on what i just read. The whole ec/ppm percveptions are just .. i don't even know how to describe it in a polite way. This is well beyond preflower, whatever that is supposed to mean. This plant is not showing an N-tox because the leaves are not overly dark nor glossy. More than one thing can cause the tips clawing. The 'tacoing' of the serated tips could be temp or RH related - too high / too low, respectively. If this is from your diary, it looks like you've already reduced fertilization a bit because the plant is a bit lighter from week 5 to week 6. In week 6 you have some signs of interveinal chlorosis. I don't see any twisting that you mention. So, nothing is very clear right now. The symptoms do not point to 1 answer. I see a lot of fluctuation over the weeks in your diary, too. A couple weeks ago you had darker foliage and light green new growth. That's a sign of too much p or k.. so review how you've adjusted your fertilization lately and maybe that will help clear things up. Stop trying to follow some anecdotal nonsense and observe and react to the plant to make decisions.. don't just add p/k if the plant shows no demand for it. It's not foie gras. you cannot force feed a plant. If you've been waffling around with fertilization formula over the last few weeks, that a major part of what you are seeing now.