Beach rocks/shells? How do I make them safe?

[brigid_marie]

I am a native Clevelander and now live and teach in an itsy bitsy rural town. I went home this past weekend and gathered rocks and smooth shells for my 10g (which sports a "natural" look). How do I make these safe for my tank and fish? How can I be sure? What should I be watching for when I test?
Or if I should just scatter them in my flower pots...let me know.

Also, sidenote: I had to use an alternate copy machine this morning at school and had to wander through a storage room to get there and found about 5 20g's and a couple 10g's that looked like they've been sitting there for awhile. I asked my principal about it and she thinks I might be able to have a couple of them! Although I can't totally justify having aquariums in a music classroom, or cramming another in my apartment....but I'm an addict, I'll find room!

[fish_freak]

Just bring the rocks and shells to a boil for a bit then rinse them in a strainer and you should be all set to add them to your tank. Just so you know shells will nautraly increase the PH of your tanks so depending on what you keep you may want to go against haveing them in the tank. Also you may want to pour some vinegar over the rocks and see if any fizz after a few minutes. If this happens then you may not want to use these rocks as they are soft and may leach chemicals such as lime and iron into your tank and also fluctuate you PH.

[boulderman1]

i always soak my rocks in a bleach/water solution and then rinse very thoroughly, this is a sure fire way to avoid intorducing any foreign growths/life etc. as for shells, they will alter your tank chemistry, i would stay away from shells for the most part

good luck