Help with Orange Spot

I am 25 days into plant life. (Day 17 hydro). Overall I have had no major problems. However my concerns at this point are starting to rise. Equipment are as follows:

T5 Flourescent Lighting
10 gal Eb and Flow
FloraMicro, FloraGro, and Flora Bloom (mixed per 10 gal spec)
PH 5.5-6.5
PPM-not sure

As of now the height is 8" and the width on the widest palm leaf from tip to tip is 12"
The light is around 1" from the tips at this point.
The canopy is so dense and thick that the lower branches are not (what seems to be) getting enough light i am assuming. They are starting to wilt.
The other problem is I have one spot on the biggest palm leaf which is orange. I am afraid it will start to spread. I am going to change the nutrients, I flushed with water only last night and stopped watering until the res change. Is there anyone who can give advice? Always look forward to hearing from the pros. Pics will accompany later..