These girls are on their deathbed. Help!

Is this light burn??

Little bit of info, i suspect overwatering because of the droop, however the soil has completely dried between waterings...once a week with 1.5 gallon pots. They are under a 1000 watt MH lamp, about 18" away. All 12 of my plants look unhappy, but on this strain, the leaves are turning dark brown and dying.
the are in kellog patio plus. The runoff has been coming off pretty high.. Around 7.4 and i have tried to correct it with lower ph'ed water.

I would suggest a heavy flushing of your soil. Ph the water to 6.5 and flush with 2-3 times the volume of your soil eg. If you're growing in a 1gal pot use 2-3 gallons of ph'd water. This should help significantly.

So you think it's nute burn? Or lockout?