please help with plant nutrient def.......

Plants are 1 month old in ebb & flood..The plants are growing,but i think i have some kind of def,i tried everything and i still can't figure out what's wrong,i use cal-mag plus but i hear to much mg will lockout Nitrogen..the leaf edges curl up with a rust/brown color spot on each edge tip and some of the leaf tips are yellow with a spot as well...Can someone please help me out.....I use pure blend pro grow,cal-mag plus,and aquashield in r/o water..ppms 250...res temp 62-70..room temp 72-78..humidity 50-60..Ph 5.8 .Thanks alot...the pics were taken right b4 lights out,for some reason they just doop like that, and thanx again.