Pytanie ogólne

LED do this even if feeding a plant well. If you have powerful LED, you should expect it to occur. Yes, p-def can cause this, but i track and log what i feed at all times. i can amp my P up with a 0-45-0 TSP without changing anything else... the purple petioles never go away, but i definitely start to get P-tox symptomes not too far above 60ppm. Since i did not change any other ppm value per molecule fed, i can be very confident of what i observed. they are worse at the top where exposed to light the most - just another sign it is related to the LED. So, becareful. don't just blindly amp up P in your mix... do it slowly and allow some times to observe plant's reaction.. if you start to see P-tox symptoms without any visible improvement on the petioles' colors, then you know it had nothing to do with the amount of P you feed. -- this is much easier to do in a soilless or hydro context, but you can do it with soil too, albeit with less resolution about the moving parts. you definitely want to try, but if all you get is a P-tox, accept that it was the wrong path taken, take a step back, and either try something else or accept it as inevitable.