Drooping leaves turning brown. Help!

1. Plants are 6 weeks since sprout
2. I use a 600watt MH
3. Soil is maricle grow miracle grow
4. Humity and temp are kept steady
5. I have 12 plants under one light, although... only 3 have this issue.
6. I have a fan (on low)

If anyone might know what might cause this i'd appreciate it if you let me know. If you need more info, ask away!

As for me it looks like calmag deficiency. Did you give some?

There is no issues with the plants but those other scraggly looking things what are they clones? I dont hold much hope for them.

No those scraggly things are my freinds, he asked me to help revive them i just got them from him last night, he started from seeds and had no idea on what he was doing, using on cfl on them, and proably overwatering them, but i think i can fix them.

One cfl*

And no i didnt give them any calmag. But i started feeing them miracle grow plant food two weeks ago, i put half a teaspoon in 1liter of distilled water and split that among 11 plants and then an hour later actually watered them, i water them when the soil is looking dry, about 1 time every 2 days