Everything seems to be going good, except the issue with the top leaf pictured below. I am not sure what this is, and would love some help/advice. She has bee fed 1 time and watered with RO water and CalMag, Fulvex, and Seaplex every other time. This seems to be the only problem area.
How close to the light is your plant. If you have a good amount of space your problem is nutrient burn. Just flush some of the salts from your soil.
The new growth seems healthy, nothing big to worry about.