Doin' something Wrong, but what

I'm trying to start growing purely for economical reasons, however, I can't get them to survive. I need some help.

Here's my setup:
1 gal 2 plant hydro system with 2 and a 1/2" baskets
100 watt HPS bulb apprx 10" from plant/seed
Seed starts in jiffy pellet till roots reach basket
Liquid karma teaspoon/gallon every 3 weeks of so
Light is on timer for every 18hrs on 6 off
Black Jack seeds

Here's the kicker, The plants shoot up about 3" or so, very fast. then they wither and die. wtf am I doing wrong?

try flourescent lights, hid is too strong for seedlings.

That might be it, but the plant dies after its sprouted it first leaves. Is it to strong for new plants? How do I know when to start using it?

Try the flours. That hps is more for the flower stage.

CFL's would work