The Puffer Forum

You are going to be doing water changes anyways, so you can add the rocks etc while the water is lowered for a water change. No big deal. Adding sand will be messy though if there's already water in the tank, that's why I'd do it first if you can.

Krill isn't a very good diet, but I don't know what she means by he's trying to cough something up. Maybe he has something stuck in his teeth.

dry heaving ?? He opens his mouth and jerks backwards a couple of times

I wouldn't worry about it, or live rocks, or sand right now.
I would just get the 65g tank filled/dechlorinated/heated, add in a few cups of marine salt, and acclimate the puffers into it.
That is far and away the best thing you can do right now.