Small yellow/brown spots on leaves in DWC.

[erfingaurus]

First time Hydro gro.

This plant has been in DWC for about 5 weeks. started 1/6 nutes after week 3, then 1/3 nutes (Big Grow and Photosynthesis plus) after 4 weeks.

I'm noticing little small yellow/grown spots on the older leaves. Any idea what this might be? Not seeing any root rot and they lights are pretty close, about 12 in away.

Any ideas?