Maybe I'll laughed out of this forum the day after joining. But I have to ask.

Waterbed bladders: Now I am thinking of the plain old bladder types without baffles or anti-wave "stuff",  are pretty tough. After all, they hold lots of weight in water. Is there any reason these bladders wouldn't hold air??? Is there some molecular thing I couldn't begin to understand, why they would leak air?

Air means no weight. Air means no heater. Air means easy add and subtract for firmness.

Something we tried a year ago: Someone we know was giving away a waterbed of the type that consisted of a foam and upholstered base with 7 individual tubes to fill with water. We took the freebie. Before my husband was available to help me with the water, I filled the tubes with air to be sure none were leaking before we put water in them. None leaked and I laid on the tubes and that is when this air idea entered my mind. Long story short, when we did the water filling, it was too firm for me. When removing water to a softness I preferred, I bottomed out. (I am a heavy person.) These tubes had perhaps a 7" diameter when filled.  End of experiment .(Although I don't know why I didn't go back to air. I guess I figured I would bottom out on that, too.)

So what do you think? Different bladder, (single piece,thicker available, I presume) foam topper over. Can I create a DIY air bed???