Updating a few more photo that show the problem in more detail. Those have just been taken a few minute ago, the other pic where older.

I start to see purple stem, could it be a N deficiency?

http://img682.imageshack.us/img682/3110/img4697h.jpg
http://img514.imageshack.us/img514/9619/img4696.jpg
http://img15.imageshack.us/img15/8173/img4695h.jpg
http://img148.imageshack.us/img148/4521/img4694pg.jpg
http://img191.imageshack.us/img191/8616/img4693p.jpg



I indeed have a fan blowing right on them, i just raised it so it dont blow directly on them.

I'm also going to buy a ph meter so i can see if there is some issue there too, but I have a little question; if i buy ph down, will the one that my pet shop sell will do? or I need some specially made for plants?
Baphometh Reviewed by Baphometh on . Dry leaves, vegetation state What is your experience level? (first timer, novice, experienced...) First timer Your Equipment: .1) Type and wattage of lights. (MH, HPS, CFL's, tube fluorescents, LED's) HPS 150 watt .2) Distance from tops? just about 24'' .3) Reflector type? (cool tube set-up, bat wing, enclosed reflector, bare bulb...) Build-in Ballast (sun sytem 150 watts) .4) Is there a consistent fresh air supply? yes plenty .5) Do you have an exhaust fan and a circulation fan? yep, both of 'em .6) What are the Rating: 5