Is This Light Stress?

[Jungleboogie]

5 weeks from seed, 600w hps, northern lights auto.
18/6
I need help figuring out what's happening at first I thought nitrogen deficiency but but now I suspect light stress

 

[Toaster79]

Feed them! They're starving!

 

[Crops]

Feed them! They're starving!

He’s right I will agree they’re starving

 

[Dutchcity]

What’s your ec look like?

 

[Jungleboogie]

Thanks for your replies, I've been watering them with canna terra vega but only 5 ml per 2 litre, just watered them and put 10ml in.
I'm not sure what the ec is dutchcity, I am a novice and this is my second attempt.
Last attempt went surprisingly well with same set up.... a light and fan

Any advice much appreciated.