Major problem

Im running a bubbleponics system and all of my 24 plants are fine except this one. its top leaves wilted straight down. can anybody help?

Have you checked the bottom of the leaves for spider-mites? I've read and experienced that spider-mites can sometimes cause curling of the leaves. It looks like that's what they're doing to me, possibly incorrect though, but always worth checking.

I've had crummy clones in the beginning turn into my best plant over time, just something to keep in mind.