1st grow -am I killing them?

hey everyone...anyone:
I'm into my 1st grow and having some trouble that I cant figure out. I need help before I kill them before they have a chance...

Details and pics are:
3 plants from bagseed in my home-built cabinet. one is larger than the other two and I' hoping to top it to let the others catch up. Bet, plants look stressed and wilting, especially #1. Nute burn? Lighting shock? Leaves are drying and curled.

Water was at 600ppm per GH nute directions, added tablespoon of Epsom Salt on 11-19-08.

Water was bottled purified, PH to 6.0 (using drops, hard to tell)

Nov 21 had lights (250 watt MH) on 18-6 at 12 inches above #1 (lowered three times from 24 inches above)

Plant 1 show signs of burn or shock, but good roots, so I pumped out about 5 gallons and replaced 4 to cut nute level.

Now: all plants showing stress. As pics show

Temps: 78 -82 F, good airflow; water temp = 80 F; PPms = 480 -580; PH = 6.5 – 6.0 using drops and color (hard to tell).

Cab anyone tell me what this looks like? I've searched many, many threads but cant seem to figure it out. I'm thinking lighting issue or PH, or nutes...? Any and all help is very appreciated!

are those plants in rockwool? they look overwatered to me and in a DWC the usual suspectin overwatering is that the plants are in rockwool that is submerged in the water. if they are in rockwool it cannot touch the water at all. put the water level at 1/2 inch below the rockwool and top water until roots penetrate the bottom of the rockwool.
if they arent in rockwool then i dont know what to tell you

I agree that they look saturated and over watered.

Aha, yeah these are still in the starter cubes and the water is pretty high. That might expalin it. I'll drop the H20 level.. thanks!!

I do have fans in the cabinet - 1 in fresh air, 1 exhaust and one just circulating. PH has been constantly high but getting a good measure is tuff with the drops and color - I have a meter in the mail...

Most likely over-watering because they are small and because you also have CFLs, it's not gonna be extremely warm. I heard that most of the water that the plant uses is to keep a constant temperature inside the leaf. Also, if you are giving them nutrients then cut that down too becoz they are only small and require little of everything... hope i help.

Thanks Kash. I'm dropping the water and the nutes both.

600 PPM nutes is just fine, You need to watch your PH more carefully, you want the PH of the res to be around 5.6 to 5.8. You are PHing the water you put in to 6.0, but you are Supposed to PH correct the Res tank, not the water going in.