Plant going pale=mg?

Hi guys.

Looking for some help here my c99 are going pale in color?

They come out my propagator on the second of febuary,went into 3" pots with allmix,then p[otted up to thier final pots (6.5) ltre last wednesday,now they look like they ar losing their green and fading away,is this the start of mg defiency? Temps are 78f lights on around 72 off...time for some epsoms or what?

thanks in advance ukg.

looks like Mg to me, i had the same problem, i'd foliar with ph'd water and some epsome

but wait see what the others think..
welcome to the site, im also from the uk :)