True is that you are quite on a heavy side with food, but there are no major signs of burn, so there is absolutelly no need to drop your food more than half to 1,2 like somebody suggested. Hes literally in every thread spliffing out that parroted potassium defficiency bullshit. You have more than that one deficiency appearing on your leaves. If your issue goes on after you lower your EC, try to rise your pH to 6,2 - 6,4. With such strong food at pH 5,5-6,0 you might have your coco in low 5 most of the time. BTW when you plant to flip them? Looking crowded already…