plant deficiency please help peeps!

[o MR BUD o]

hey guys i have 3 plants in pots (soil) and 1 of them is showing signs of discolouring on some of her leaves!!
does anyone out there have any idea of what the deficiency is called that she is desplaying and maybe what corsed it!!

she is 2 weeks into veg
the soil is called all mix
its a pre mix soil with nutes already in it and comes with an EC of 2.4 (ppm 1200)
the soil comes with a PH of 6.6

the other 2 plants in soil dont seem to be showing the same deficiency in there leaves!!

thanks people!!!

 

[TaylorMade420]

just flush if you aint sure mate, 3 times pot size in litres of water

 

[NEEDhelpBAD]

If the leaves are turning light green or yellowish it could be a nitrogen deficiency