I'm annoyed by having to post another question but oh well. Yesterday evening I increased the PAR from 370 to 400 in center. This morning the top fan leaves were pointing straight up and so I raised the lights a little. I later looked and saw discoloration. Light burn?
I would tend to agree with ya, just do what your doing for a couple days and see if they get worse it could be a minor magnesium deficiency and if so a bit of Calmag or Epson salt tsp per 3.6 L should bring it around..
I agree with Whiteybulger1814, it's just a bit of calcium deficiency, that lighter part will tend to turn brown. If you correct the deficiency right away, the spots will be smaller, but you won't have too many problems anymore.