Cal Mag from LED too close?

light burn doesn't require cal-mag. Most "cal-mag" problems are rarely an actually cal or mag deficiency. Even when cal-mag doesn't fix it, it is still a "cal-mag" problem somehow even after that point... the horse is dead! please, stop making a mess! LoL Anyway, eliminate other possiblitites before putting more stuff into your substrate or reservoir. pH (get some .1 resolution pH strips for cheap, once you know your tap, tap+ferts and whateve relse, you are good to go and ph-up or down will remain consitent to get where you want), tds or recent fertilization if you don't have that meter, other rcent behaviour etc etc... always assume you did soemthing wrong... even when you don't, lol.. it keeps you on a safer path when troubleshooting. to be honest, who's else fault could it be with an indoor grow? (rhetorical, not aimed at you specifically). you can get awesome advice that is rock solid, and due to limited information it simply doesn't apply to your situation when it comes down to it... i know i've told peopel the worng thing, even if they don't tell me later about it.

Those fox farm nutes are super strong! Excess of potassium cause all ur symptoms and goes miss diagnosed as calcium deficiency all the Time! Flush ur medium... than give lower bloom doses and ur problem should stabilize.

I believe it's a excess of potassium causing ur calcium to be locked out.