Yellowing bottom leaves + paper thin leaves.

Hi there I got a couple problems with my plants that I just started on week 1. prior to starting the veg schedule i had a MH light on for 6 days 24 hours if that makes a difference.

i think its a nitrogen and magnesium problem but i dont know much or how to correct it! any help is awesome guys !

this one has the real thin leaves. it is starting to curl and become yellow at the tips of the older leaves

Also i should probably say that i only have the fox farm nute line. big bloom, tiger bloom and grow big.
the fox farm feed schedule tells me that i shouldnt use any grow big until week 2, and im sure "grow big" is gonna have all the nitrogen and magnesium...