I have someone that wants some of my baby apple snails who wants to put them in her planted terrariums to clean up algae and such. Can apple snails survive in terrariums?! They won't really clean all that much, will they?
If it's a paludarium it'll work as long as there's 2.5g of water per snail. Straight terrariums with no water are completely out of the question though.
And no, they don't really clean up that well, they can be pretty messy by themselves.
They are obligate aquatic so a gallon or two each of water is a must--and I agree, they create much more mess than they clean. They tend to eat algae off unevenly rather than "cleanly".
They are not efficient algae eaters at all and would need to be target fed a calcium rich diet as well. As mentioned, they would not likely leave the water to work on her terrestrial plants, so its probably just an all around bad idea.