Lower branches wilting fast.

I've got a 1 month old WWxmango in DWC under cfls on DNF two part veg nute. ph is 5.5-5.8 temps are 22-25C / water temps 15-19C

she looks really healthy, growing very fast but over the last two days the lower most shoots have wilted completely.

Does anyone know why this is?

Thanks,

need pics-could be a million things

I cut them off.

it was just the two bottom shoots, still had thier colour but looked like they were really really thirsty. just fully wilted.