Jo Ann, please read the entries above your posting in this thread. They will answer your questions, except as to where you could buy hypertufa troughs in your area.
The North American Rock Garden Society (NARGS) journal has some ads in it. There is an ad for a place called "Benedicts Nursery" (sic) in Nappanee, Indiana (574-773-2254) that says troughs are sold there, as well as tufa. (NB. This is just info, not an endorsement of this business, as I know nothing about it, or the quality of the troughs sold there.) I thought there used to be a vendor in New York state - I'll look around a bit.
