Shells from the beach ... safe for Freshwater

Has anyone picked up shells of the beach to use in their freshwater aquarium? My kids bring them home all the time.. and I was thinking putting them in the 20 gallon I want to set up for them... If so any recommendation on preparing them for the tank..

Thanks Guys..

When I use them I scrub them good with vinegar water. Kinda fizzes off the outer layer of the shell. Since they are from saltwater I never expect any parasites that would infect freshwater inhabitants. They will leach calcium into your water, possibly increasing hardness and alkalinity though. Regular water changes should keep that under control.

It's another good way to bring nature inside and keep kids interested in natural things.

PS....Don't forget to rinse them well after using the vinegar water!

Thanks FishloverRon...

give them a good soak to get any salt off of them and scrub them up and you should be fine!

I wouldn't want to put shells in my tanks unless the fish are meant to live in hard water. Smaller tanks will have more rapid fluctuations in the params too. So I think a couple shells would be okay but I wouldn't full out cram the tank with them.