Yellowing Lower leaves at 5 weeks flowering

hey guys,
this is my first grow and thus far it has been going really well. Im at about 4.5 weeks flowering, and my lowest fan leaves are starting to turn a little yellow. Is this normal or should i boost up some Nitrogen to them? facts are below. this could be simply because its the lowest fan leaves and theyre not getting much light, but not sure. also, picture of top cola attached, so let me know how you think im doing so far.

Lighting:
4 2' flourescent tubes, 2 cool white and 2 warm white
2 20watt CFLs, 2700K

Nutes:
Ive been using succulent fertilizer from home depot - 2-7-7 ratio
Epsom salt added
fertilizer, epsom salt and water about once a week or when soil dry

Conditions:
Temp between 76 (day) and 70 (night)
Humidity between 40 and 60, depending on the weather

Thanks!

a little yellowing is normal during the final weeks or budding.
although your leaf tips are curling under. look into that... Marijuana Plant Abuse

yea what oddjob said