Blue stems - Green stems why?

[keylime]

Hey keylime,

Hard to tell what you need to add without knowing what you're adding to.

I have seen blue stems in veg, in a Pro-Mix filled container grow where the temps were too low at night. And it was only some plants that were effected, not all, and they where the same strain. Growth rate was slower for the blue stem plants.

You probably need to supply some more info.
OM

Well, the veg room is 16/8, Temps 75 tops at light. and with lights out, no lower than 68. I'm running 3 part General Hydroponics... nothing else.
I have read one thread on another board with a similar problem, and there was one comment that felt it might be a lack of nitrogen.... if that's so, I really don't know...that's why I'm seeking help. Some are in hydroton, some in coco CHIPS.... but it happens in both medians. I've grown for 7 yrs.

keylime.