Curling leaves. Lights color

You need to buy proper, cannabis specific nutrients and I am sure your problems will go away. My experiences over 40 years of growing tell me P/K boosters for cannabis are excellent, they certainly add yield and there is no way I would not use them. And yes, I have done side by side experiments.

* local tap water may influence exact ppms a bit... again was a ballpark and deviating slightly wont' mkae much of a diference...

You need a well-balanced 1.2-1.5EC diet.. if not providing that, you need to feed more. "1/3rd" strength means a totally different thing to each person, so that's not a good way to communicate it. In hydro/soilles oyu provide that at all times. it's not a danagerous level of nutes for any stage of life. possibly some light or heat stress too with the tacoing of leaves. 25-30C is the range you want to stay in.. you go much higher and you see problems. Genetics will impact the point at which this occurs. Eliminating light stress as a possibility is easy, but not with these pictures. simlply look at internodes -- are the too long? too short? just right? that'll tell you if the light is too intense or eliminate it as a possibility, here. Looks more likely to be heat-related from these pictures. basic ppm rundown for a good ballpark to start in: N 120-130 P 50-60 K 180-190 Ca 100+ Mg 75ish S 100-110 this is a light EC around 1.3, i beleive.. you may need more, but the ratios are rock solid. Local VPD will impact the overall concentration you feed at but ratios will remain similar. Also, drop N 10-20ppm heading into flower. REcent studies show that amping up p or k in flower doesn't actually do anything... if someoe anecdotally saw "something" it was more likely they merely were udnerfeeding either one in vege phase, lol. When scientifically researched and compared to a control group, bombing it with p or k in flower doesn't add to yield nor quality.... just added expense and an psyhological E-peen.

I think you got something more than nutritional going on. How are temps in your reservoir? Growing anything besides roots in there? How do your roots look? I also like to run my pH a little bit lower in veg. 6.2 is OK in flower but I'd shoot for closer to 5.8 in veg.