Use of terra cotta wine storage cylinders

[ajm1961]

Just wondering if anyone has heard of using terra cotta wine storage cylinders in an aquarium, as a cave for plecos or synodontis?
Is it safe?

[karjean]

A lot of people are using Terre Cotta pots in the aquarium. As long it was not used for anything and after a good cleaning i do not see any problems.

[ajm1961]

That's what I thought as well. The only thing I don't know is whether there is a difference in composition between terra cotta pots and these cylinders. They are reddish in colour, like the pots, but I noticed some small stone chips in them. There is no glaze as well (which is good). Does terra cotta have some type of stone in its fabrication, and any type of mortar which could be dangerous? I guess I could try a cylinder in one of my smaller tanks with a few inhabitants to see its safety...