Really worried please help

Hi all I feel that I'm going to lose these babies and don't know what to do.
They are northern light fem.
I am doing a dwc with 5.8ph canna a-b vega with cal mag and super thrieve.
Second week veg under 250hps duel spectrum hps.
Temp and humidity is 70f 60%
I have been using less than recommended dosage as I don't want to over nute.
Because I am using less than recommend dosage am I under nuteing and as the result my plant leaves are turning yellow brown and dying off ?
Sorry for the hps pictur in advance

Please help

Keep an eye on the new growth and maybe check your roots

Sent from my D5503 using Rollitup mobile app

There isn't much root popping out underneath so it is hard to see what's happening

This might help: http://www.growweedeasy.com/marijuana-symptoms

Thank you for your input guys. I have been searching high and low on all sorts of sites and I have narrowed it down to cal mg and maybe nitrogen deficient.
Is there anything I can add apart from my normal nutes to give addition nitrogen in my dwc ?

Give it full str veg nutes and calibrate your ph meter, doesnt look right.

Its not getting enough nutes and i think a wrong ph could be the reason. Your feeding it and it looks starving, usually ph issue.