Heavy fast yellowing

bro, avoid mid grow flush. this is one of the critical mistakes when growing mj. Flush should be done at the end of flowering.If you have nute burn during earlier phases, just reduce amount of nutes you are giving to them and save the flush for later phase.When leaves start to fade to yellow after a succesful flush, it is impossible to turn them back to green as all vegetative growth was done and now there is no room for extra nitrogen intake as you are in flowering. Many growers learned it that way,including me. No mid grow flush,only adjust your feeding well and flush at the end of flowering prior to harvest. If you don't see signs of burnt leaves or stunted growth, high ppm won't hurt , you can flush all the nutes out a couple of weeks before harvest. now should just keep feeding it with bloom nutes until the end.