Surely they would have an easy, logical way to...

Oh wait! Now I remember a similar scene here with the pool pump. It has to have the sand changed every year... through the top opening that already houses a pipe that leads to 8 fragile lateral lines; if you break them you are really screwed - guess how I know that. If you get the filter sand into them you're not screwed; you're doomed. And, of course, the pump has to be winterized be removing several plastic screw-in plugs placed strategically out of reach of any tool known to human-kind, Then said plugs need to be replaced in the spring, IF they can still be found and are miraculously unstripped.

Good luck with the waterbed.