Hi! The problem affects both the hydro and soil peppers, so I don't think it can be a nutrient issue. The LED light is the only thing in common (or a pest, but I haven't seen any aphids...)
Thanks guys for the quick answer. I'm not sure how to upload pics, but please find attached a link to my iCloud shared folder: https://www.icloud.com/sharedalbum/#B0fGJDfWGg3RuO