can someone help me identify this problem

Can you see the spots in the picture?

pics would be better determined if your red lights are off
I'm pritty sure most are guessing it's better clear picture to get a clear answer. Hope it helps

Another guess is you need pk because of you red leaf stems if they look like this when normal lights on then you need pk but I would recommend clean water for first two watering and achieving a good 20 odd % run off, not only this time but allways make sure you get a good run off it will help with future problems, add your nutes accordingly not what the label says (try and see what your plant says)by going on slowly with nutes.
I'm not guessing about the pk deff because that's what I and my fellow friends grow are experiencing.