Hojas manchas marron

Those are not signs of deficiencies or toxicities, the blotching is most likely due to the foliar spray (too heavy drench will cause droplets to act as "magnifying glass" when lights are on and burn your leaves). As for the foliage damage it seems like either Fungus gnat or leaf hopper. To treat it do use the foliar spray mixture recommended to you but don't overdo it your plant is very fragile in those young stages!! also try to mainly spray the bottom of the leaves since pests prefer to lay their eggs/larvae on the underside of the foliage. Try adding a yellow sticky paper to catch the pests living in your grow space and to identify them accurately. Good luck and happy growing :)