Athosanswered grow question 6 years ago Well you are following a set feeding schedule, Tang's. But what kind of soil are you using: light, heavy / all mix? And I don't see you measuring pH nor EC/PPM. For a 20 liter pot, you sure started feeding early, even if it's light mix.
Besides the golden spots, you also have leaves with curling edges, which make me think of nutrient burn, either because you are feeding too early, too strong a solution or too often (or a combination of the three).
Give the plants plain pH'ed water for a week or two, you might even want to do a mild flush.