Yesterday I watered with fertilizers. The dosage is 0.8 grams per liter. PS in the area of 5.5. The instructions say 4 grams per gallon. 1 gallon = 4.55 liters. Everything seems to be correct, so I do not understand what the problem might be.
In my humble opinion, the plants are still too young for fertilizers. The yellowing could be water chlorosis. They don't seem to be burned from nutrient excess, nor do I think it's a nutrient deficiency; they're still very small.
We don't follow the label on the nutes. We properly feed with a ph ec reader as to not over feed. Directions on the label are just about always for growing in soil in the great out doors. The amounts on the bottle will destroy plants indoors. Cheers