seedling tips yellowing !?!

i did few grows before , but this is the first time this happens to me




ppm 400
ph 5.5
temps: air conditioned room between 75-80

I'd run at 5.7-5.8, 200ppm. You using tap or RO water? How are the roots and res temp?

i did before with same specs, and it worked turned out a dude, its fine will collect pollens ,

this one is a female white widow x big bud, could it be the genetics ? i've seen blue cheese before leafs change colour a bit
i use RO water, res temp 72 t0 77, roots didn't appear out of hydroton yet, just one root line few days ago then it disappeared , you think its the ppm??


this is my current male pics , it sprouted april 1st 12

It seems a bit high for that small of a seedling. What all nutes are you using?

just harvested the male today, the roots have turned brown, even though using subculture-b,
i hope this seedling won't have the same issue cuz females need longer time , the male took 6weeks, but females need 12 or more for veg and flower,

and today i saw roots coming out of the bottom of the pot of the seedling so its cool, and the next leaf set looks okay, but now am afraid in like a month the roots would turn brown and die,, what can i do ? is there anything else better than subculture-B?