leaf discoloration, first time grower

ok so i've been at this for a couple weeks now, and everything was going great, i got a 600w hps light, hung it 30 inches above the plants, came out that night and 2 of my plants were sad, it's been 3 days and now every one of them has this wierd white/yellow stuff on them... this is my first attempt, did i kill them? any advice would be excellent, thank you!

Bump... Any help at all? I'm starting to worry....

Pics are not great but it look like heat burn to me....I have some girls that are 12 days old and my light is at the top off my 180cm tent, try to put your light higher for now their are to young to take a 600W too close.
good luck

that doesnt sound good... thanks for the help!

Should I use a different light? Will they recover?

CFL is best to start them but as I said before I use a 600w with mine because my CFL is in my mother plants tent, you just need to be more careful with it. Leave a lot of space until they reach 3/4 weeks. I think that they will, make sure that the light is high, have a fan blowing in the room and check the temperature, use an extraction fan to keep your air fresh and temperature down.
keep us posted......

Actually go buy some real potting soil. Fox Farms - any of their soils. Your medium looks more than questionable. KISS.

Agree 100% wit CFL 6500K - all can throw at them. 1 per plant in a cheap bowl reflector if possible.

Those little babies don't really need 600 watts just yet. I would use flourescents until they are around 6 inches tall.