Welcome to the community,
@N8erade !
There have been a number of threads on the General Vaping board on stuck tanks....might be worth a search. Just from reading through some of them, there are a number of suggestions.
Try something that will give you better grip. Latex gloves, wrap a rubber band around the base, or a vape band.
Some say to put the tank in the freezer for a while, that it will shrink the O-rings or something like that. You might then also need one of the grip suggestions above.
If you get to the point you want to use a pliers or vise grip, use a cloth between the jaws and tank to (hopefully) eliminate damaging the tank....and do not put them on the glass!
Once you manage to get it open, I will take a dab of juice on my finger and run it around the O-rings to (hopefully once again) make it easier to disassemble in the future. And when you assemble the tank, don't go crazy cranking it hard....let the O-rings do their job. Easier to tighten it a little more should it seep a little juice.
Good luck and hope you can get it disassembled, cleaned, and working well for you!