necrotic spots

Noticed that some of the top/middle fan leaves have started getting this pale color between the veins and some brown/necrotic spots towards the ends of the leaves. Any idea what it could be? Strain: Huckleberry (flipped 12/12 3 days ago) Medium: RDWC hydro Ph: 5.8 EC: 1.7 Water temp: 68F Room...