ditto on what
@Aqua Man said. FF mixes are pretty strong, and when when cut with cocoloco, it can sometimes be overwhelming. The leaf damage probably occurred a little while back as sometimes damage can take 2 weeks to be visible. Adding more stuff can throw the entire balancing act off, and it can be maddening to try to fix lockouts and imbalances. I use a 20-20-20 general fert during vegging, but I also add some soil modifiers...ie Compost/manure, wood ashes, ad a small handfull of times release general purpose fertilizer... not sure of exact ratios but good for most stuff (but not 20-20-20... I save that for feedings). The compost mix supplies plenty of micronutrients and Iron, while the wood ashes provide some P & K, and the Promix already has some Calcium built in for buffering. I feed once every 12 days or so once they are growing fast.
The point of this? You don't benefit from using too many nutes, as plants don't need nearly what most people use and usually manufactures recommend 4X what more experienced growers tend to use. You also can avoid nutrient lockouts and conflicts.. You have made a good attempt and I hope it continues in a positive direction. As long as you keep learning, you will continue to get more valuable experience. There is a lot of conflicting info out there, but the hardest part of growing for newer growers is waiting long enough for them to finish flowering, and going easy on some of the powders and potions. Most are just fertilizers in differing ratios and sell for a lot more than they cost to make. Love the plants, not the propaganda!!
