thats interesting, but have you done any other research on this product, i have a commercial catalog that lists sheet products for farm ponds so both products are used, there must be advantages and limitations, seems like plant roots, or burrowing turtles, or scouring from excessive water flow, would eventually cause leaks, which seem to be easily repaired, of course my little pond has vertical sides that need structure, but it is strange that vinyl, and concrete seem to be the only products used in ornamental ponds, since many are not vertical.
Plant roots do not cause leaks, otherwise every little park pond and a lot of reservoirs would be in big trouble (they tend to have trees dotting their shores too, much bigger, stronger roots to deal with than an urban pond). I imagine a burrowing crayfish could be a problem if he was doing that in the middle of the pond. Scouring is not a problem I'm familiar with, although I wouldn't line a swift stream with it. Considering that sodium bentonite is really just a kind of clay, and that it does form waterbodies where it occurs naturally, I thought it would be a more natural and possibly more stable option. Both hard liner and soft liner ponds seem to have problems with ripping/cracking but the clay would mould around whatever penetrates it (including plant roots). Its price was also tempting for a thrifty future college student
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