Anthropolis
Canna Jedi in training.
The prevailing thought is not to prune autos usually, but some growers do remove some sometimes. I'd advise for now, not to remove leaves until the deficiency is halted. Just in case it gets worse. :smoking: Yeah gotta check the pH, couple fresh pics. 
--- Oy, have you checked the soil pH, and what your inputs are pH'ing at? FuxFarms has been horrid shit for many lately, with half cooked badly acidic soils,... that said, if it's all lower leaves, light starved, and likely tapped out for their N as well, like GB mentioned,... I need pics, not in HPS please, to confirm,.. this lights' color rendering is lousy for diagnostics!