The terracotta pots have been fired in a kiln so all I do is rinse them well. I get the smallest ones and the hole is so small the fish can't fit through it, I usually have my son take out the bottom so the fish can go all the way through it. He scores it then a few sharp taps with a hammer it comes out. Then use sand paper to make sure there are no sharp edges. If the pot breaks we just glue it back together will aquarium silicon. You can always use a marble glued to the bottom of the pot if you want to plug the hole. I have 4 different bettas with pots in their bowl or tank and only one uses it. I tie java moss on mine for more of a natural looking cave. The pipes from home depot made out of is fine. I do boil those.
