Depends on the goby ... that having been said, I've got a few gobies in my QT right now, and they're almost done with the process. Bare-bottom QT with plenty of various sizes of PVC piping, this is a 40Breeder. There's an Aqua-Clear 110 providing filtration, with a good-sized powerhead providing additional water movement and oxygenation. Currently in the tank are three blackray shrimp-gobies (Stonogobiops nematodes ... who names a fish after a family of worms?!), one female yellow watchman goby (She's gray. More misleading names!), and a yellowline cleaner goby.
They don't seem to require sand . . . Other gobies might.
Hi Mike! I agree with Maritimer. It would depend on the goby, but they don't usually need the sand for such a short amount of time. If he's super stressed out you could place a small container with dry, clean sand in it in the QT for him. It may help his stress level, but has never been needed for me.