I wouldn't worry. I grew lotus for years in ponds lined with 45 mil rubber....both dug ponds and above ground block ponds....and never had the lotus puncture the liner. There are some sturdier plants that will, like Thalia sp., but the only problem I had with the lotus was extricating them from the folds in the corners without damaging the runner.
Truth is not what you want it to be; it is what it is. And you must bend to its power or live a lie.”― Miyamoto Musashi
"Knowledge speaks, but wisdom listens." ~ Jimi Hendrix
“The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge.”― Stephen Hawking
Craig