Hi guys, what a kind of deficiency is this?

I'm along the same thought process as the others in this question. Lower your ambient temps "25-28c", keep that reservoir cool "18-22c", lower the EC of the feed its an auto they don't feed as heavily, over feeding can cause them to enter flower early. The symptoms do look like potassium but this may self correct when the other two items are first addressed. I would not go giving it any more till you fix the above problems. Check you roots and confirm they are healthy and white and not slimy or have foul odours. Some feeds with dies will discolour them but not a crazy amount. Should they have any issues you need to clean out your DWC and treat the problem. Hydro guard is one option many others out there like peroxide to kill off the microbes growing on the roots. Good Luck!

He leído su diario y es por la temperatura. Su solución nutriva puede que tenga una temperatura alta y la planta no asimila bien sus nutrientes. Su ph está dentro de los parámetros bajaría unos puntos de ec. Su puede baje la temperatura de su solución a 22⁰. Suerte

bro i just saw your diary that plant cant take 1.8 EC lower it try with 1.6 EC also if that 30C water inside the pot then put ice bottles cool it down and also check the roots if they are white and not sticky then u just need to lower EC and download PPFD meter app to check DLI/18 make sure is not more then 40-45 good luck 💪

If you think it's a deficiency it has to be a Potassium deficiency, but I'm personally leaning towards heat stress because your leaves aren't just turning yellow but also curving down or getting twisted. Your light isn't very close but you have very strong lights so it can still be the case that these leaves are suffering from high temperatures. Good luck with the rest of your grow, hope you find a way (that's viable for you) to control the issue

Could maybe not be a deficiency. I had a quick look and maybe check a few things pH. Possibly bit high EC for that stage in DWC. Maybe nute burn. Especially if temps get high and she pulls more water up therefore more nutes Possibly light intensity. 40 cm seems a bit close. Maybe back off a bit. A good thing I use is a free app called PHOTONE that measures light intensity. . Aim for 5-600 ppfd. Clean airstone regular/make sure enough oxygen and water temp acceptable And finally good luck