Yellow Purple Fan Leaves, Problem?

So my grow has been going pretty good but today I looked at the bottom fan leaves and they are starting to yellow a little, with a few brown spots. On one of the leaves, there is a purpleish haze. What kind of problem could this be? I searched the forum but found that most purple on the leaves was associated with darker green leaves. I will try to have some pics posted soon. Oh ya, I'm growing in soil, under 2 105W CFL 6000K lights. Thanks.

post a pic. if you are flowering it may be normal

Do you ph test? Do you have a mositure meter? Do you use fert? At what strenght?

ok Heres some pics. The problem is really only on a few of the very bottom fan leaves. I think they ares suffering from a nitrogen deficiency? I have some 30-10-10 fert that I think I will water them with to try to correct the problem. Any advice would be appreciated. Thanks

http://img490.imageshack.us/my.php?image=1000991bo2.jpg

Do you have a big temp drop at night?

The temp usually goes from about 80-85 F in the day to about 68-70 at night. Would that be the cause for the purpling though?