Outside, 2 weeks or so into flower, 5 feet tall. I am using metanaturals base+bloom, twice a week. I have interveinal chlorosis, 4 fan nodes from the bottom, 1 fan node has died off already. Can fungus gnats cause this (saw little white bugs when watering/looking into seriousness)?

Maybe magnesium lockout from PH and if so should I check the soil ph - or does it just matter for future water?