Diagnosing problems on thin serrated leaves is harder than on broad indica foliage, since discolouration spreads differently and shows later. Magnesium issues in particular tend to look like light burn on narrow leaf plants. A visual guide to common deficiencies in sativa dominant growth is available on https://hazesativaseeds.com with photographs at different stages. Checking runoff pH before reaching for any bottle solves a surprising share of these cases.
