What's wrong with my plant ?

Again I have been away and I have came back to this mess
It is on the 3week of 12/12 on a dwc system it's a northern light strain using nova bloom cal mag 4gal bucket 600w hps. 5.9ph ro water
For some reason the plant doesn't seem to want to flower and lots of the leafs seem to be eating itself away.
Sorry in advance of some the hps pictures as I could not take them out of the room. Please give me some advice.

I think your pH is too low, hindering the plants ability to take in nutrients. Also, are you sure you don't have any light leaks during your dark period that are preventing flowering?

I don't think light leak is the issue as I have another two northern lights and a big bud x northern light going on at the same time and they are are doing fine. Ph could be an issue as I haven't been here to check. As I have been back to check it has been a steady 5.8 to 6.5.
But for some reason the plant doesn't seem to want to flower like the rest.

3 out of 4 ain't bad. Pitch the bitch and give the others more light homie loc!!