Nute burn or deficiency?? (Pics)

I have noticed a few gold spots on the edges and center of a few leaves. I am not sure if it is a early stage of K deficiency, nute burn or heat stress. I haven't seen anything in my reference books that really look like these spots. My Homebox stays at a temp of 80-84 F during the 18 hr light period with a RH of 30-35%. The fans and ventilation stays on 24 hrs. The pH is kept at 5.8. The large plants are week 3 from seed. Has anyone seen these type of spots before??

I grow in soil so Idk anything about hydro but here's a link i've been passing around I hope it helps.... International Cannagraphic Magazine Forums - The Complete guide to Sick Plants,pH, and Pest troubles!

Thanks for the info. I think it may be from a organic spray i use to prevent mildew and bugs or maybe a calcium deficiency. They seem to still be doing well so far. I guess i will just have to keep an eye on them.

I think it was a little burn from the organic spray and a build up of salts. I flushed with some Flora Cean today and they are looking really good. I will change the rez with fresh nutes tomorrow.

A few of my fan leaves have rust colored spots and i think it might be because my pH is at 6.5 in the morning and i bring it down to 5.7-5.8 every day and my ppm stays at 1150 for vegging.