brow spots on the leaves veg

I have brown spots on my leaves im probably a month and a half into veg im using a 150w hps. why do I have brown spots in veg? an I use neptunes harvest organic fish fertilizer but every couple weeks or so please help is it a burn or wat?

I'm sure someone more experienced in soil gardening will be along shortly. I attached a handy chart that shows (somewhat since it is small) common deficiencies. You can google "Plant deficiencies chart" and you will find it. From there you can adjust your feeding and soil ph accordingly. Good luck!
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