leaves are clawing 5th week of flower

help me out please. i can't seem to find the problem,
im using a soil perlite and vermiculite medium
AN's hobbyist line up (was at 844 ppms) 40th day of flower
400w hps 2 11w cfls
5 gal pots
yellowing started from the bottom-up and in the veins
a little less than a half-gal of water about every two-three days

Turn your HPS off and people might be able to tell you what it is.

ill take pics tmw right before the lights come on

yoo check out my new pics on the forum

What the ph are you watering? I find if my ph is out to lunch I experiance the same problem. 6.3ph soil is what I run