yellowing problem

Hi i have a little problem dont think its much, Reading up it might be a light casuing this problem just want some input just incase its not.
I will check this thread as im about to have surgery in 8 hours.
any ideas would be greatful.
strain is super silver haze auto aswell only 2 weeks old from seed.
no nutes been uses yet only rain water since im on tank

and they are under 2 600 watt hps lights

Lightbleaching? How close are ur lights?? What size room u in?

Lights are 60cm away and its in a 2x2 metre tent, heaps of air moving around its just that one on the side of the tent itself which has done it and only 2 leaf's on that one plant, rest are fine in the area.
I was hoping it was not the soil i was using

hmmmmmmmmmmmmmmm

Hi and thanks to all, my mate has just picked me up for my surgerys, He has just had a look and said its over watered and to cut back for a few days, thanks for all who have answered me

Looks like a little a MAG issue....