Common problem with these
tanks when you over tighten them, you only need to finger tighten them and not screw them down hard.
You may have to wrap something around the tank and use some grippers or a vice to get it open, although I'd try ..first
You could try running it under hot water with the air holes shut to warm the
juice up around the grommet and then try..
Rubber jar grippers, two of them.. or push the bottom part to the glass and with the other hand grip the glass tank and turn, you may break it though.
I know my friend had the same problem and she ended up buying the cage tank and then smashing the glass one apart and picking all the glass out, the caged ones do seem to come apart better but this is obviously a last resort.
Cage -
Mini Nautilus Cage Tank