Plant leaf looks sick please help

Plant has a curl down on the end and it ain't really growing any help ?

Just like when you go to a emergency room or to see a doctor they need information on what may have caused the problem. I.e ph, ppm, temps etc.

your picture is kinda blurry, but looks like it is advanced powdry mildew, post a better pic if you can, but if it is PM, i think they may be to far gone, it looks pretty bad.
Sorry bro.
If it is PM, you may have to kill them all, bleach your space and start over.

I also have a problem with my leaf, however, it is lime green and it appears the new leaves are also growing lime green. PH 6, stealth cab hydro setup, 7 days from sprout, pink salad auto, using root riot cubes and hydroton rocks as medium, no nutes yet, 180w veg cfl's. There is clearly something wrong with the one plant but the others do not seem affected?