Vikane gas (Sulfuryl fluoride) is what they use when they tent for termites.
It's made by Dow Chemicals and they advise removing your aquariums and houseplants.
When I was in property management we had to tent several buildings over the years, and there were always tenants that had aquariums.
The termite company had a clause in the contract that released them from any liability, but they had good advice for anyone who couldn't move their tank.
Make sure you talk to a manager or consultant from the company and explain your situation.
They've dealt with it a thousand times before and might have some new or better advice than I can give.
From my unqualified and spotty memory, you'll need:
A heavy plastic sheet
Duct tape
Enough air tubing to reach from the tank to your airpump(s) about 10-20' away from the outside of tent
Airpump(s) and airstone(s)
The top of the tank has to be completely sealed with a plastic vapor barrier.
Visqueen makes some serious multiple layer, aluminum core, gas barrier plastic sheets for protection against Radon gas, but almost all the tenants used heavy-duty trash bags or regular Visqueen construction plastic instead.
Remove everything that's on the tank, or sticks out of the tank except for the air tubing and the cord to a powerhead.
Duct tape the plastic sheet down to the glass, not the plastic frame. (it's easier to scrape the glass clean with a razorblade later)
Get it as airtight as possible, but don't stress about it not being completely 100% airtight around the tube and cords.
Since you are pressurizing the tank with the outside airpumps, the positive pressure will vent your excess air out those tiny gaps, and keep the Vikane from coming in.
It's just simple physics when you really come down to it.
On a side note, the powerhead should be pointed at the surface to help with the oxygen exchange in addition to the airstone(s).
Good luck, and remember if something goes wrong,... this conversation never happened.