Help, nute deficiency? mg? light burn?

Hi I have a plant at about 2 weeks veg in a dwc bubble bucket under a 400w [MH] ~18inches above the top of the plant.

I fed the plant full strength micro/bloom 5 days ago (lucas), and have added back in about a gallon of water since

pH is ~5.5

In the last couple days, the plant's growth has slowed and has started developing small brown/yellow spots on random leaves, and it appears that new growth has some yellowed areas as well.

I added 1tsp/gal epsom salts when I fed, and just now, in attempting to correct the issue.

Should I dump and refeed with a fresh batch of nuted solution?
Is this a light burn problem?

Please help, this is my first grow, and I would like it to be a success

pics attached.

Thanks!

Are you sure your PH is at 5.5? on a calibrated meter?

that is my first guess.

Are you using a ionizer in the room or area?

What's the water temp and how are the roots looking. Let us know..... JR

And a lot of nute problems take a few days to show any change, be patient...

Positive its at 5.5, just calibrated my meter, and took a reading, roots are looking healthy, slightly brown near the top, but I'd attribute it to nute staining. I do not have an ionizer, just running a carbon filter in line with my exhaust fan.

not sure exactly what the water temp is, but its cool to touch, pic of roots attached. pic makes them look a somewhat darker than they actually are.


I'm fairly confident they're just fine

oh, also, I said i was under hps, i meant mh...