Yellow/Browning on bottom fan leaves

I'm about 5 weeks into my grow, growing 8 week autos under 2 130w cfl's, 1 warm, 1 dual band. I'm just not sure if the fan leaves dying and falling off is normal, as i've read that. I've also read that it could be a nitrogren deficiency, Magnesium or calcium. Or could it be nutrient lockout? I'll post some photos.

I'm using 7-4-10 nutes with all the micro nutes you could ever want.

Nice, but a seldom asked question......
How about a pic from further back of the whole plant?
It looks to me like a burn, or your leaf tips were sitting in wet soil, one or the other.
What kind of soil are you using, and are you still vegging or into flower?

Yeah i can't get to my grow at the moment so i'll have to wait to get the picture. but i'm growing in premium potting mix. They started their flowering too.