One can get almost anything for a price. We have a big industrial plastics dealer around here who specializes in exotic chemical pipe. You name it, even big diameter teflon. But the price per foot would scare the fleas off every dog within a ten mile radius. Cellcore ABS is much cheaper, but quite heavy in big diameters. I've got Sonotube in stock here, but wouldn't trust that simple wax layer to protect the integrity of the tube for long; and pickling it with epoxy would probably unravel it too. So I'm not going to test that idea. The thing to do would see if those plastic substitutes for concrete tube will accept an ABS cap which can be altered to make a light-tight chem fill cap. I won't try this myself, because I've got enough working tubes for now already. But it sounds like a fairly easy and inexpensive way to do it.