My 1st Grow, HELP me

i have some trouble with my 2 veg plants.
margin of top leaves are like dry .and stem is reddish purple . large leaves are dark blue green . light is 250w MH and 20 inch is height . temperature is 20c-24c an humidity between 55%-65 % . i fed them very little . my guess is Salt up and Phosphor deficiency . what i have to do ?

yo...how is your drainage?? mine did the same thing, only got alot worse before i realized there was absolutely no drainage.

i mix peat moss & perlite 80%-20% . in each watering no excess water out from drainage hole . you think my problem is watering ?