Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Ditto. Tanks build to hold air (reptile habitats, terrariums... will not stand up to the weight of water. If you can find out for sure how it was built, that would help. If the prior owner actually bought an aquarium and just used it for something else, then that would be OK. (as long as it does not leak, of course)
Make it into a riparium. Small amount of water and mostly air (soil, rocks, plants) would probably be safe.