Past the first week. The plants had stretched the stem too much due to the lack of initial light. Now I have lowered the substrate and changed the lamp to a blue light. The results are evident: the leaves, the stem and even the roots have developed better. Solution always at the same concentration. Go on like this :) !
@Taito, It is the first time I have done a hydroponic cultivation (and second production that I do in my life :)). 4 days ago the plants were really frail, now they are gaining strength.
I'm confident! Thanks for your comment!