Hello
@Hawkbo ! It looks like a little bit with potassium deficiency but in theory its more possible to be nutrient burn from the fulvic acid (and since you are an experienced grower i am going to assume that there were no over/under water issues and stuff like that to create a potassium deficiency). That's part of the chelation. Fulvic acid beside its chelating properties ( binding the free ions and protecting them from reacting with different charged ions and precipitate ) it makes the nutrients moving freely inside the plant because of its very low molecular mass.It is very possible that this burned your plant (i have seen this happening before with bioag full-power). The better the quality of the fulvic acid the higher the risk of burning them. After all one of the main reasons of using fulvic acid is to reduce the amount of nutrients! Happy growing ! 👍