Wedding Cake by Zamnesia

I have only done some defoliation this week. We're having problems in the tent! 3 out of 4 plants show defeciences. I realised the other day and tried to correct nute mix by making it stronger and adding some grow nutes. I don't know what the problem is. Looking at leaf deficiency charts it looks to me like there is a Zinc deficiency. I don't understand why. The largest plant in the tent, a Wedding Cake, is looking great. She is starting to show the initial signs of over feeding after the last few days of feeding corrections, though, and I don't want to give them any stronger mix. They all share the same nutrient mix. I'll flush them tomorrow. Hopefully they'll be okay after that and recover...