Truck bed liner is completely water proof and there is no way any sized crocodilian would tear through it. There is always the chance of a leak but as long as there is complete coverage of the lining material there should not be any.
As far as concrete goes, the key is to use Rapid Set mortar mix. Although it has a short working time it does not crack or shrink. You can mix small batches at a time and trowel or hand spread it onto diamond wire that you have fastened onto whatever frame you have designed.
We just finished the lumber part and today the tanks go to be sprayed with bedliner.
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1.0 Albino American alligator, "Smoke"
1.1 American alligator,"Al Bite Ya & Molly"
1.1 Purple Albino Reticulated Pythons, "Gumbo & Abita"
0.1 Eastern Gaboon Viper, "Gabbie" Recently passed away at 24 years old
Help me find this snake!