Like I said, it's a sealant and not an adhesive. Please don't take offense to my comments. I am simply suggesting there is a product that is better for the application, and all things being equal, I'll use the better product.
As far as whether or not your tanks hold water with GE1, I'm sure they do. They may never fail. They may fail tomorrow. It's always a crap shoot, but the better odds are with the better product.
HTH