Need help diagnosing a problem with my plant

I started with 4 plants in a Hydroponic system, two of them ended up being male so I had to kill them. I use Aerogarden Extra LED. I started using the LED light that came with the Aerogarden, which is only 30W. Three weeks ago one one of the larger female started showing flower signs, however some of the leaves started turning yellowish. I thought its due to the light and the low power so I purchased Advanced Platinum Series P300 300w. I placed the light 2 days ago about 18" above the plant. However the plant started showing more yellow leaves (about 19 of them). I have attached a photo below, does anyone know what is going on here? thank you guys.


Nutrition:
Fox Farm Grow Big Hydro Liquid
FoxFarm Big Bloom
FoxFarm Tiger Bloom
FoxFarm Beastie Bloomz

pH: 5.8-5.2
EC: 1.8-2.2
Humidity: 40% - 50%
Temp: 71F - 76F

Overfed.

Nute burn bad!!!

I dont think its nute burn as most leaves are hardly affected and with nute burn most leaves are affected. It looks like light bur/bleaching. how close are they to the light?

Light stress often first appears around the edges of leaves, while inside veins stay green



This cannabis seedling is being burned by too-close LED grow lights



http://www.growweedeasy.com/marijuana-symptoms