How long can plants survive in Aero/Nft without water?

Let's say if your pumps fails while you're asleep. How many hours before they are irreversibly dead?

I would guess 4 - 24 hours depending on how big the roots mass is and much water they can hold. I've had seedlings start to get droopy just from taking too long to change the res (weed breaks or getting distracted).

They don't really need all of their roots though... you can chop some off and they don't seem to mind much. So if you had mature plants most likely the outside of the rootball would be dried out but the inside could still be wet for a long time... so plant might make it. This is mostly stoner theory though... I have never tried.

Yeah, size does matter.

Thanks y'all.