There is a good size plastic barb(part of the tank)that pops into a rubber grommet. It is VERY difficult to pull this tank out of that grommet; but it will come out. Get some lubrication into that grommet if you can, and it's also useful to have 4 hands pulling it up and gently rock back and forth, side to side slightly. Yes, it's a blitch. I thought I was going to break mine when I was pulling out, it was so hard. (I'll probably hear about that last comment)