Yellow On Outside of Leaves 2 weeks old

my plants are only 2 weeks old and have started forming fairy light yellow on the edges of the leaves, its not a vast amount but still just a little on the edges, i have 4 daylight bright bulbs 3 fans 1 big one taking in air 2 little ones taking old air out, i have uploaded a picture in hope of help, any suggestions will help me:(

Thanks for the great help an suggestions everyone =)) OOOO i mean (NO ONE:thumbsup:)

Fill out the trouble shooting form, and try to get a less fuzzy pic if you can. This will get you more responses, and accurate responses.
Here is a link to the form. :hippy: http://boards.cannabis.com/plant-pro...ing-forms.html