Those tanks have been around for a very long time. Jelly fish tanks are referred to as kreisels. They are very expensive because the glass or acrylic has to be curved and not just simply stuck together. I would not recommend any nonprofessional in keeping pelagic jellyfish. They are very sensitive organisms and some have a potential of harming you. Filtration is difficult too since its extremely easy for them to get stuck in them. I have cared for jellyfish before and its not easy. First off you need to breed your own copepods etc.. They can not catch dead food. You need to be extremely wary of water params and monitor them like a hawk. If you like jellyfish leave it to professional set ups and go see them at a public aquarium.